ライフサイエンスコーパス: archaeal

1 and nuclear target Fe/S proteins are mainly archaeal.

2 elated with the relative abundance of MCG in archaeal 16S rRNA clone libraries, and were (13) C deple

3 ncing of the V4 region of both bacterial and archaeal 16S rRNA gene was used to characterize the micr

4 structurally conserved between mammalian and archaeal ADPGK, and site-directed mutagenesis has confir

5 ms that drive DNA-guided DNA silencing by an archaeal Ago.

6 tivities and the transcript abundance of the archaeal ammonia monooxygenase gene (amoA) in nitrifying

7 Nitrosotalea genomes with 19 other archaeal ammonia oxidiser genomes.

8 ; qPCR) of Thaumarchaeota 16S rRNA genes and archaeal ammonia-monooxygenase gene copy number (qPCR) w

9 ur analyses infer a relatively small-genomed archaeal ancestor that subsequently increased in complex

10 compact systems originally inherited from an archaeal ancestor.

11 , but rather originated by fusion between an archaeal and a bacterial SemiSWEET, which potentially ex

12 RNA genes on the chromosome and their use in archaeal and archaeviral genetics.

13 o distinguish N2 O production resulting from archaeal and bacterial ammonia oxidation in soil microco

14 Viruses are trifurcated into eukaryotic, archaeal and bacterial categories.

15 stable isotope incorporation for individual archaeal and bacterial cells to constrain their potentia

16 es have also been found scattered in several archaeal and bacterial genomes, unassociated with CRISPR

17 ubunits/factors characteristic for eukaryal, archaeal and bacterial RNAPs and thus provides a unique

18 arya, plant SBTs are more closely related to archaeal and bacterial SBTs, with which they share many

19 Phylogenetic evidence for a fusion of archaeal and bacterial SemiSWEETs to form eukaryotic SWE

20 ic of head-tailed viruses and, unusually for archaeal and bacterial viruses, a nearly complete replic

21 elicase responsible for unwinding DNA during archaeal and eukaryal genome replication.

22 nd contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss rec

23 Furthermore, the archaeal and eukaryotic Ncs6 homologs as well as phospho

24 NusG, referred to as Spt5 in archaeal and eukaryotic organisms, is the only transcrip

25 ors enhance the processivity and fidelity of archaeal and eukaryotic RNA polymerases.

26 eins shared highest sequence similarity with archaeal and fungal enzymes, which peak in two redox tra

27 s to elucidate the responses of soil fungal, archaeal, and bacterial communities using an N and P add

28 al mechanism for TSS selection by bacterial, archaeal, and eukaryotic RNAP.

29 A number of bacterial, archaeal, and eukaryotic species are known for their res

30 ly use acyl-CoA to modify diverse bacterial, archaeal, and eukaryotic substrates.

31 ere, we measured fecal-associated bacterial, archaeal, and fungal communities of dairy cows from 2 we

32 ryotic ATP synthases are well characterized, archaeal ATP synthases are relatively poorly understood.

33 Phe281 and Glu285, which are conserved among archaeal ATP-dependent RNA ligases and are situated on t

34 30 years ago, it has been believed that the archaeal B-family DNA polymerases are single-subunit enz

35 g, and nectar secretion, whereas the role of archaeal, bacterial, and animal transporters remains elu

36 s annotated DNA and RNA sequence data of (i) archaeal, bacterial, eukaryotic and viral genomes from c

37 ated effects of varied levels of N inputs on archaeal, bacterial, fungal and chlorophyte community co

38 at is different from the one observed in the archaeal beta' clamp-Spt4/5 complex.

39 y stained electron microscopy (EM) models of archaeal box C/D sRNPs have demonstrated the dimeric sRN

40 be classified into any existing subgroup of archaeal BR proteins based on the protein sequence phylo

41 stral CPN that formed distinct bacterial and archaeal branches.Chaperonins (CPNs) are ATP-dependent p

42 In contrast to the situation in eukaryotes, archaeal Cdc45 and GINS form an extremely stable complex

43 at explains how these larger fluctuations in archaeal cell cycle events contribute to cell size varia

44 eukaryotes, we investigated whether and how archaeal cells exhibit control over cell size.

45 Interestingly, the archaeal cells exhibited greater variability in cell div

46 Very little is known about how archaeal cells orchestrate transcription on a systems le

47 Given that archaeal cells share characteristics with both bacteria

48 ped a soft-lithography method of growing the archaeal cells to enable quantitative time-lapse imaging

49 ion of genes encoding these unique programs, archaeal cells use gene regulatory networks (GRNs) compo

50 A total of 10%-12% of all bacterial and archaeal cells were found in the particle-associated (PA

51 rface of adjacent protein layers destabilize archaeal chromatin, reduce growth rate, and impair trans

52 taxonomic markers for ecologically important archaeal clades.

53 era viennensis EN76, the type species of the archaeal class Nitrososphaeria of the phylum Thaumarchae

54 o propose the name Hadesarchaea for this new Archaeal class.

55 gnificantly to global methane emissions, but archaeal cold adaptation mechanisms remain poorly unders

56 so contained a nearly complete genome of the archaeal commensal Methanobrevibacter oralis (10.2x dept

57 We characterized bacterial and archaeal communities in a chronosequence of restored tal

58 nced biocathode CH4 production, although the archaeal communities in both biocathodes converged prima

59 e investigate the structure of bacterial and archaeal communities inhabiting the detritus within the

60 Bacterial and archaeal communities inhabiting the subsurface seabed li

61 Thus, although the archaeal communities were similar in the two biocathodes

62 Geochemical profiles, archaeal communities, and bacterial communities were ind

63 The native ammonia-oxidizing archaeal community (comprised primarily by Nitrososphaer

64 The phylogenetic composition of the archaeal community (reanalysed from published work) divi

65 nt dynamics and global correlations based on archaeal community composition and temperature.

66 thanobrevibacter arboriphilus, dominated the archaeal community in the ZVI-free and ZVI-amended bioca

67 The relative abundance of archaeal community markedly increased upon H2 addition w

68 Fungal and archaeal community structures and compositions are mainl

69 y analysis of similarity tests indicated the archaeal community structures of smooth and pustular mat

70 uted in global oceans and dominate the total archaeal community within the upper euphotic zone of tem

71 eatment of brain abscess should contain anti-archaeal compounds such as imidazole derivatives in most

72 s we have defined monophyletic bacterial and archaeal DGR lineages that expand the known DGR range by

73 ion except in the most oxic samples, whereas Archaeal diversity was not consistently different betwee

74 Smooth mats possessed higher archaeal diversity, dominated by Parvarchaeota.

75 s or just microbial dark matter of expanding archaeal diversity.

76 omparative genomic analyses of bacterial and archaeal diversity.

77 overhangs, are extended using a thermostable archaeal DNA polymerase.

78 which is missing for all naturally occurring archaeal DNA polymerases, provides a framework for engin

79 ng the genomes of Archaea, the mechanisms of archaeal DNA transport have remained a puzzling and unde

80 the first time to our knowledge described an archaeal DNA transporter.

81 and mediate the segregation of bacterial and archaeal DNA.

82 ms, including the first reported Cas9 in the archaeal domain of life, to our knowledge.

83 autes is conserved through the bacterial and archaeal domains of life and suggests that eukaryotic Ar

84 Using in vitro assays with an archaeal DsrAB, supported with genetic experiments in a

85 c archaea have provided unique insights into archaeal ecology and paleoceanography.

86 e ecotype structure observed in bacteria and archaeal ecotypes.

87 The archaeal enzyme relaxes both negatively and positively s

88 haeal lipids to include numerous unsaturated archaeal ether lipids (uns-AELs).

89 lish novel geochemical relationships between archaeal ether lipids and key environmental-, energy-, a

90 omal RNA sequence alignments from bacterial, archaeal, eukaryal and organellar ribosomes, using nucle

91 ic replisomes and evolutionary links between archaeal, eukaryal, and bacterial replication systems.

92 n and evolution of the conserved core of the archaeal/eukaryotic replisome.

93 e reduction has been the predominant mode of archaeal evolution, our analyses infer a relatively smal

94 DNAs that are major agents of bacterial and archaeal evolution.

95 nd the structurally and functionally related archaeal exosome complex from Sulfolobus solfataricus.

96 Archaeal family-D DNA polymerases (Pol-D) comprise a sma

97 2 secretion systems (T2SS), type 4 pili, and archaeal flagella assemble fibres from initially membran

98 We can now show that the archaeal flagellar filament contains a beta-sandwich, pr

99 e FlaF protein that forms the anchor for the archaeal flagellar filament.

100 The archaeal flagellar system has no homology to the bacteri

101 The archaeal flagellar system is simpler still, in some case

102 understood that the N-terminal domain of the archaeal flagellin is a homolog of the N-terminal domain

103 cessary for either assembly or motility, the archaeal flagellin outer domains make extensive contacts

104 tude of N2O production were accounted for by archaeal functional gene abundance.

105 ing partnerships with an array of bacterial, archaeal, fungal, protistan, and viral associates, colle

106 teria ASADH is replaced by the cover loop in archaeal/fungal ASADHs, presenting the determinant for t

107 ng murine BPI (mBPI) expressed on halophilic Archaeal gas vesicle nanoparticles (GVNPs) for the treat

108 is placed the split between Plasmodium GatB, archaeal GatE, and bacterial GatB prior to the phylogene

109 ansfers, and gene losses contained in 31,236 archaeal gene families to identify the most likely root

110 o mitochondria, whereas SBPase arose from an archaeal gene resident in the eukaryotic host.

111 ing to the bacterial genus Smithella and the archaeal genera Methanoculleus and Methanosaeta.

112 Here I describe recent developments in archaeal genome maintenance, including investigations of

113 Consortium (GSC) for reporting bacterial and archaeal genome sequences.

114 e below the photic zone, where bacterial and archaeal genomes and proteomes undergo a community-wide

115 in systems are ubiquitous in prokaryotic and archaeal genomes and regulate growth in response to stre

116 yotic RNA polymerase (RNAP) II system, while archaeal genomes are more similar to bacteria with dense

117 he bza gene content of several bacterial and archaeal genomes is consistent with experimentally deter

118 The evolution of bacterial and archaeal genomes is highly dynamic and involves extensiv

119 ce of two components of the MVA pathway from archaeal genomes led to the discovery of an alternative

120 n 36 groups of closely related bacterial and archaeal genomes reveals purifying selection affecting A

121 A survey of bacterial and archaeal genomes shows that many Tn7-like transposons co

122 sable elements present in most bacterial and archaeal genomes that play an important role in genomic

123 collection of closely related bacterial and archaeal genomes that provides several tools to aid rese

124 all index (4.2 GB for 4078 bacterial and 200 archaeal genomes) and classifies sequences at very high

125 probable horizontal origin) in bacterial and archaeal genomes.

126 putative encapsulin systems in bacterial and archaeal genomes.

127 transposons present in diverse bacterial and archaeal genomes.

128 over 1000 completely sequenced bacterial and archaeal genomes.

129 ne content and gene order similarity between archaeal genomes.

130 was built in 2008 to annotate bacterial and archaeal genomes.

131 sites and reconstructed RbkR regulons in 94 archaeal genomes.

132 river in the evolution of core bacterial and archaeal genomic and proteomic properties.

133 fundamental drivers that shape bacterial and archaeal genomic properties remain uncertain (3-7) .

134 genus Methanosarcina is the only identified Archaeal genus that can utilize acetate via acetate kina

135 Further, the archaeal GINS*Cdc45 complex contains two copies of Cdc45

136 ian synaptic monoamine transporters, and the archaeal GltPh, which is the prototype for the "elevator

137 At each level, archaeal GRNs consist of a hybrid of bacterial, eukaryot

138 that this ubiquitous and abundant subsurface archaeal group has adopted a versatile life strategy to

139 Mountain (California) pointed at an abundant archaeal group, dubbed 'G-plasma'.

140 A new study finds that archaeal histone dimers can multimerize into extended su

141 wraps around an extended polymer, formed by archaeal histone homodimers, in a quasi-continuous super

142 We report the crystal structure of an archaeal histone-DNA complex.

143 Here, we show that FANCM and its archaeal homolog Hef from Thermoplasma acidophilum inter

144 TPase of Thermoplasma acidophilum (VAT), the archaeal homolog of the ubiquitous AAA+ protein Cdc48/p9

145 Crystal structures of the archaeal homologue GltPh have provided important insight

146 ic' proteins in Archaea, indicating that the archaeal host cell already contained many key components

147 Current data support scenarios in which an archaeal host cell and an alphaproteobacterial (mitochon

148 identified and were found to replicate in an archaeal host species closely related to Metallosphaera

149 genomes of viruses that infect bacterial or archaeal hosts (viruses of eukaryotes will be added at a

150 sites, and secondly by generating a chimeric archaeal human protein.

151 of the putative genes in the spindle-shaped archaeal hyperthermophile fuselloviruses have no sequenc

152 acterial ancestry, whereas Group II CPNs are archaeal in origin.

153 The archaeal initiation factor TFE and its eukaryotic counte

154 Bacterial and archaeal isolate sequence space is still far from satura

155 Further biophysical analysis of a complete archaeal KEOPS complex reveals that Pcc1 facilitates KEO

156 it is dispensable for t(6)A biosynthesis by archaeal KEOPS in vitro, raising the question of how pre

157 ranches in the genomic tree of bacterial and archaeal life and illustrate the unique and exciting adv

158 uplicated maeB within an ancient halophilic, archaeal lineage formed a putative pta ancestor.

159 tive complete genomes from all bacterial and archaeal lineages down to the genus level.

160 ators showed significant variability between archaeal lineages, the conserved core of RbkR regulons i

161 for the protein in DNA damage repair in all archaeal lineages.

162 We report the archaeal lipidome in SPM from diverse oceanic regimes.

163 However, past studies of archaeal lipids in suspended particulate matter (SPM) an

164 Furthermore, adaptation of archaeal lipids in the deep ocean remains poorly constra

165 cking certain structural features of natural archaeal lipids results in improved membrane integrity,

166 We extend the known inventory of planktonic archaeal lipids to include numerous unsaturated archaeal

167 s that mimic some key structural features of archaeal lipids, such as: 1) single tethering of lipid t

168 abitats and thus represent a major source of archaeal lipids.

169 We demonstrate that the homohexameric archaeal MCM helicase associates with orthologs of GINS

170 Here, we present the structure of the archaeal MCM helicase from Pyrococcus abyssi in its sing

171 ovide evidence that an open-ring form of the archaeal MCM homohexamer is loaded at origins.

172 n-dependent recruitment of the homohexameric archaeal MCM in vitro with purified recombinant proteins

173 Our recent crystal structure of an archaeal MCM N-terminal domain bound to single-stranded

174 Eukaryotic and archaeal MCM proteins are highly conserved.

175 Moreover, some archaeal MCMs are polymorphic, and both hexameric and he

176 In fact, archaeal MCMs are powerful tools for elucidating essenti

177 ybrid of bacterial, eukaryotic, and uniquely archaeal mechanisms.

178 led unexpectedly diverse non-methane-cycling archaeal members.

179 Archaeal membrane lipids known as glycerol dibiphytanyl

180 enzyme and a binary Ago-guide complex of the archaeal Methanocaldococcus jannaschii (Mj) Ago.

181 we describe the crystal structures of these archaeal (Methanocella paludicola) NHEJ nuclease and pol

182 core structure similar to the one present in archaeal methanofuran variants.

183 Bivalves host archaeal methanogenic symbionts carrying out preferentia

184 yryl-CoA mutase and a recently characterized archaeal methylmalonyl-CoA mutase, allowed demonstration

185 The archaeal minichromosomal maintenance (MCM) helicase from

186 enomics, and computational methods used with archaeal model organisms have enabled the mapping and pr

187 The motor of the membrane-anchored archaeal motility structure, the archaellum, contains Fl

188 Further, with just archaeal N2O production, we could balance high-resolutio

189 The archaeal NCX_Mj (Methanococcus jannaschii NCX) system wa

190 Archaeal NHEJ polymerases (Pol) are capable of strand di

191 Using this system, we reveal that archaeal Orc1-1 fulfills both Orc1 and Cdc6 functions by

192 ile Pyrococcus furiosus, it is unique to the archaeal order Thermococcales.

193 standard and stress conditions in the model archaeal organism Halobacterium salinarum For yeast, our

194 Here, we report that Argonaute from the archaeal organism Methanocaldococcus jannaschii (MjAgo)

195 -binding by the MCM N-terminal domain of the archaeal organism Pyrococcus furiosus occurs specificall

196 lobacterium salinarum, a hypersaline-adapted archaeal organism, grows exponentially at the single-cel

197 Extremophile archaeal organisms overcome problems of membrane permeab

198 y complete replication apparatus of apparent archaeal origin.

199 g a ribokinase-like tertiary fold similar to archaeal orthologues but with significant differences in

200 Our results provide evidence for an archaeal PCNA 'tool-belt' recruitment model of multienzy

201 Like the bacterial counterparts, archaeal PfAgo contributes to host defense by interferin

202 ith respect to function and specificity, the archaeal PfAgo resembles bacterial Argonautes much more

203 ns can be found in fifteen bacterial and two archaeal phyla.

204 ojects have revealed numerous little-studied archaeal phyla.

205 uenced identity) from 47 bacterial and three archaeal phyla.

206 DPANN phyla compared to other bacterial and archaeal phyla.

207 consistent with the typical distribution of archaeal phylotypes in marine environments.

208 Members of the archaeal phylum Bathyarchaeota are widespread and abunda

209 he host cell is related to Lokiarchaeota, an archaeal phylum with many eukaryotic features.

210 anisms from 24 known bacterial phyla and one archaeal phylum.

211 clease activity of bacterial, eukaryotic and archaeal PNPase homologues in vitro.

212 The archaeal population and the overall microbial community

213 The archaeal population of the MEC fed 0.02 g FAN/L was domi

214 Archaeal Pri S can bypass common oxidative DNA lesions,

215 Eukaryotic and archaeal primases are heterodimers consisting of small c

216 Eukaryotic and archaeal primases are heterodimers consisting of small c

217 oxidation, is better described by low-oxygen archaeal production at the oxygen minimum zone's margins

218 bstrates are recognized and processed by the archaeal proteasome, by virtue of a direct interaction w

219 Eukaryotic and archaeal proteasomes are paradigms for self-compartmenta

220 report SILAC for quantitative comparison of archaeal proteomes, using Haloferax volcanii as a model.

221 chia coli JS1 strain only in the presence of archaeal PSTK, indicating the conserved nature of the PS

222 and DNA damage-induced splicing, in which an archaeal recombinase RadA intein splices dramatically fa

223 In eukaryotic and archaeal replication, primase is a heterodimer of two su

224 Here, we report that archaeal replicative primases (Pri S, primase small subu

225 Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the

226 tional taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed acr

227 Transcription initiation of archaeal RNA polymerase (RNAP) and eukaryotic RNAPII is

228 tances across the DNA binding channel of the archaeal RNAP.

229 Archaeal RNase P is a ribonucleoprotein made up of one c

230 wever, the number and location of K-turns in archaeal RNase P RNAs (RPRs) are unclear.

231 tate kinetics experiments, we also show that archaeal RNaseH2 rapidly cleaves at embedded ribonucleot

232 oting disagree regarding the position of the archaeal root.

233 'double K-turn' module in type A and type M archaeal RPR variants.

234 escribes the fascinating discovery that some archaeal Rubiscos contain a built-in assembly domain ins

235 es including the poxviruses, some phages and archaeal rudiviruses.

236 he structures of two prokaryotic homologues, archaeal SaTRIC and bacterial CpTRIC, showing that TRIC

237 es not present in the predicted bacterial or archaeal secreted proteomes, indicating that fungi putat

238 nd metagenomics were used to detect specific archaeal sequences in brain abscess samples and controls

239 we analyzed an additional 151 newly sampled archaeal sequences.

240 The archaeal sheath amyloids do not share homology with any

241 the most important players in bacterial and archaeal signal transduction and also occur in reduced n

242 us reduced skin moisture with an increase in archaeal signatures.

243 successfully applied to a limited number of archaeal species and has never been reported in Thermoco

244 Our study of the quinone inventories of 25 archaeal species belonging to the phyla Eury-, Cren- and

245 We isolated 4 archaeal species for the first time from human, includin

246 In hypersaline lakes dominated by archaeal species, iron levels are extremely low and subj

247 es across diverse eukaryotic, bacterial, and archaeal species, suggesting they result from positive s

248 e explains how diphthamide, a eukaryotic and archaeal specific post-translational modification of a h

249 consortium consisting of: (i) an engineered archaeal strain to produce methyl-coenzyme M reductase f

250 These results pave the way for generating archaeal strains carrying inducible suppressor tRNA gene

251 ow available for 6193 complete bacterial and archaeal strains publicly available in RefSeq.

252 For example, the archaeal Sulfolobus solfataricus minichromosome maintena

253 rchaeota, Nanoarchaeota and Nanohaloarchaea) archaeal superphylum.

254 ving the way to a molecular understanding of archaeal swimming motion.

255 Mammals host diverse bacterial and archaeal symbiont communities (i.e. microbiomes) that pl

256 ur understanding of ecological range for key archaeal taxa in a model freshwater wetland, and links t

257 Archaeal taxa varied according to redox conditions, but

258 atory, particle association of bacterial and archaeal taxa was assessed by iTag sequencing and qPCR g

259 e group of 189 ubiquitous soil bacterial and archaeal taxa, with these taxa exhibiting similar temper

260 chaeal termination activity (Eta), the first archaeal termination factor capable of disrupting the tr

261 The identification of the beta-subunit of archaeal TFE enabled us to reconstruct the evolutionary

262 ng natural product, we hypothesized that the archaeal tfuA and ycaO genes would be responsible for po

263 [3Fe-4S] cluster similar to the methanogenic archaeal ThiI.

264 Here we constructed a consensus unrooted archaeal topology using protein concatenation and a mult

265 The archaeal transcription apparatus is closely related to t

266 re reflected in changes in the bacterial and archaeal transporter proteins, we generated an extensive

267 A root for the archaeal tree is essential for reconstructing the metabo

268 challenging the traditional topology of the archaeal tree.

269 We have compared this archaeal type IB enzyme to its human mitochondrial and n

270 and/or function of the structurally related archaeal type IV pili is unknown.

271 dwide, revealing a wide distribution of four archaeal viral families, Ampullaviridae, Bicaudaviridae,

272 owever, there is a paucity of information on archaeal virion structures, genome packaging, and determ

273 p., MTIV provides a new system for exploring archaeal virology by examining host-virus interactions a

274 ghts into the emergence and evolution of the archaeal virome.

275 be determined by further exploration of the archaeal virosphere.

276 general, there are no universal genes in the archaeal virosphere.

277 Our understanding of archaeal virus diversity and structure is just beginning

278 oubles the number of candidate bacterial and archaeal virus genera, providing a near-complete samplin

279 are few connector genes shared by different archaeal virus modules.

280 s from 116 genomes allowed dissection of the archaeal virus network and showed that most groups of ar

281 rks of eukaryotic and bacterial viruses, the archaeal virus network is sparsely connected.

282 insufficient sampling to the sparsity of the archaeal virus network remain to be determined by furthe

283 hot spring environment to characterize a new archaeal virus, Acidianus tailed spindle virus (ATSV), t

284 Here we describe a new archaeal virus, tentatively named Metallosphaera turrete

285 virus network and showed that most groups of archaeal viruses are evolutionarily connected to capsidl

286 w family of archaeal viruses.IMPORTANCE Many archaeal viruses are quite different from viruses infect

287 the first study demonstrating recognition of archaeal viruses by eukaryotic cells which provides good

288 ndependent origins of the distinct groups of archaeal viruses from different nonviral elements, provi

289 Archaeal viruses have evolved to infect hosts often thri

290 rovides good basis for future exploration of archaeal viruses in bioengineering and development of mu

291 Little is known about how archaeal viruses perturb the transcription machinery of

292 Here, we selected two archaeal viruses Sulfolobus monocaudavirus 1 (SMV1) and

293 We constructed a bipartite network of archaeal viruses that includes two classes of nodes, the

294 nd unclassified, cultivated and uncultivated archaeal viruses.

295 ese unique, ubiquitous, and extremely stable archaeal viruses.

296 IV as the founding member of a new family of archaeal viruses.IMPORTANCE Many archaeal viruses are qu

297 from other known bacterial, eukaryotic, and archaeal viruses; this finding suggests that viruses inf

298 Key metabolisms (bacterial and archaeal) were measured, and the rates of oxygen product

299 Here, DNA binding by the archaeal XPD helicase from Thermoplasma acidophilum has

300 ral and biochemical studies of the monomeric archaeal XPD homologues have aided a mechanistic underst