Crystal structures of three protozoan homologs of tryptophanyl-tRNA synthetase.
Tryptophanyl-tRNA synthetase (TrpRS) is an essential enzyme that is recognizably conserved across all forms of life. It is responsible for activating and attaching tryptophan to a cognate tRNA(Trp) molecule for use in protein synthesis. In some eukaryotes this original core function has been supplemented or modified through the addition of extra domains or the expression of variant TrpRS isoforms. The three TrpRS structures from pathogenic protozoa described here represent three illustrations of this malleability in eukaryotes. The Cryptosporidium parvum genome contains a single TrpRS gene, which codes for an N-terminal domain of uncertain function in addition to the conserved core TrpRS domains. Sequence analysis indicates that this extra domain, conserved among several apicomplexans, is related to the editing domain of some AlaRS and ThrRS. The C. parvum enzyme remains fully active in charging tRNA(Trp) after truncation of this extra domain. The crystal structure of the active, truncated enzyme is presented here at 2.4Å resolution. The Trypanosoma brucei genome contains separate cytosolic and mitochondrial isoforms of TrpRS that have diverged in their respective tRNA recognition domains. The crystal structure of the T. brucei cytosolic isoform is presented here at 2.8Å resolution. The Entamoeba histolytica genome contains three sequences that appear to be TrpRS homologs. However one of these, whose structure is presented here at 3.0Å resolution, has lost the active site motifs characteristic of the Class I aminoacyl-tRNA synthetase catalytic domain while retaining the conserved features of a fully formed tRNA(Trp) recognition domain. The biological function of this variant E. histolytica TrpRS remains unknown, but, on the basis of a completely conserved tRNA recognition region and evidence for ATP but not tryptophan binding, it is tempting to speculate that it may perform an editing function. Together with a previously reported structure of an unusual TrpRS from Giardia, these protozoan structures broaden our perspective on the extent of structural variation found in eukaryotic TrpRS homologs.
Department of Biochemistry, University of Washington, Seattle, WA 98195, USA. merritt@u.washington.edu
Ethan A
EA
Merritt
Tracy L
TL
Arakaki
Robert
R
Gillespie
Alberto J
AJ
Napuli
Jessica E
JE
Kim
Frederick S
FS
Buckner
Wesley C
WC
Van Voorhis
Christophe L M J
CL
Verlinde
Erkang
E
Fan
Frank
F
Zucker
Wim G J
WG
Hol
D000595:Amino Acid Sequence; D001665:Binding Sites; D016785:Cryptosporidium parvum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D018360:Crystallography, X-Ray; D004748:Entamoeba histolytica / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D014369:Tryptophan-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D015800:Protozoan Proteins; D014369:Tryptophan-tRNA Ligase
Proc Natl Acad Sci U S A. 1996 Sep 17;93(19):10128-33
8816763
Mol Cell Proteomics. 2004 Sep;3(9):934-8
15240823
Acta Crystallogr D Biol Crystallogr. 1997 May 1;53(Pt 3):240-55
15299926
PLoS Comput Biol. 2009 Oct;5(10):e1000530
19855826
EMBO J. 2000 Feb 1;19(3):445-52
10654942
J Biol Chem. 2004 Feb 27;279(9):8378-88
14660560
Nucleic Acids Res. 2008 Mar;36(4):1288-99
18180246
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 Mar 1;62(Pt 3):175-9
16511295
Protein Sci. 2000 Feb;9(2):218-31
10716174
Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15422-7
14663147
Acta Crystallogr D Biol Crystallogr. 2006 Apr;62(Pt 4):439-50
16552146
Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 1):2256-68
15572779
Acta Crystallogr D Biol Crystallogr. 1994 Sep 1;50(Pt 5):760-3
15299374
J Biol Chem. 2009 Sep 4;284(36):23947-53
19574216
J Struct Biol. 2010 Aug;171(2):238-43
20438846
Science. 2004 Apr 16;304(5669):441-5
15044751
J Mol Biol. 2007 May 25;369(1):108-28
17428498
Nat Protoc. 2009;4(3):363-71
19247286
Structure. 2007 Jul;15(7):793-805
17637340
Acta Crystallogr D Biol Crystallogr. 2006 Jan;62(Pt 1):72-82
16369096
J Mol Biol. 2003 Jan 3;325(1):39-63
12473451
Science. 2007 Sep 28;317(5846):1921-6
17901334
Proc Natl Acad Sci U S A. 2002 Jan 8;99(1):178-83
11773625
Proteins. 2003 Feb 15;50(3):437-50
12557186
Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15376-80
14671330
EMBO J. 2002 Jul 15;21(14):3829-40
12110594
Trends Biochem Sci. 1992 Apr;17(4):159-64
1585461
Mem Inst Oswaldo Cruz. 2007 Sep;102(6):757-62
17924007
Mol Biol Evol. 2007 Mar;24(3):743-56
17182897
Nucleic Acids Res. 2007;35(17):5934-43
17726052
Genome Res. 1999 Aug;9(8):689-710
10447505
Acta Crystallogr D Biol Crystallogr. 1999 Oct;55(Pt 10):1718-25
10531521
Nature. 1990 Sep 13;347(6289):203-6
2203971
Nat Struct Mol Biol. 2004 Feb;11(2):149-56
14730354
Bioinformatics. 2000 Feb;16(2):135-9
10842735
Science. 2005 Jul 15;309(5733):416-22
16020726
Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 1):2126-32
15572765
Nucleic Acids Res. 2007;35(13):4289-300
17576676
Acta Crystallogr D Biol Crystallogr. 2004 Mar;60(Pt 3):432-8
14993666
Proc Natl Acad Sci U S A. 2006 May 2;103(18):6847-52
16636268
Science. 2005 Jul 15;309(5733):404-9
16020724
EMBO J. 2006 Jun 21;25(12):2919-29
16724112
Nucleic Acids Res. 2006 Jun 23;34(11):3246-58
16798914
RNA. 2002 Jun;8(6):752-61
12088148
Anal Biochem. 2004 Sep 1;332(1):153-9
15301960
Mol Cell. 2008 Mar 28;29(6):679-90
18374644
EMBO J. 1999 Dec 15;18(24):7056-62
10601027