HMM Summary Page: TIGR00089

Functionradical SAM methylthiotransferase, MiaB/RimO family
Trusted Cutoff251.00
Domain Trusted Cutoff251.00
Noise Cutoff185.40
Domain Noise Cutoff185.40
Isology Typesubfamily
EC Number2.1.1.- 2.8.1.-
HMM Length429
Mainrole CategoryProtein synthesis
Subrole CategorytRNA and rRNA base modification
Gene Ontology TermGO:0003824: catalytic activity molecular_function
GO:0009451: RNA modification biological_process
AuthorRichardson DL, Anolik RT, Haft DH
Entry DateApr 20 1999 2:04PM
Last ModifiedFeb 14 2011 3:27PM
CommentThis subfamily contains the tRNA-i(6)A37 modification enzyme, MiaB (TIGR01574). The phylogenetic tree indicates 4 distinct clades, one of which corresponds to MiaB. The other three clades are modelled by hypothetical equivalogs (TIGR01125, TIGR01579 and TIGR01578). Together, the four models hit every sequence hit by the subfamily model without any overlap between them. This subfamily is aparrently a part of a larger superfamily of enzymes utilizing both a 4Fe4S cluster and S-adenosyl methionine (SAM) to initiate radical reactions. MiaB acts on a particular isoprenylated Adenine base of certain tRNAs causing thiolation at an aromatic carbon, and probably also transferring a methyl grouyp from SAM to the thiol. The particular substrate of the three other clades is unknown but may be very closely related.
ReferencesRN [1] RM PMID: 10572129 RT Identification of the miaB gene, involved in methylthiolation of isopentenylated A37 derivatives in the tRNA of Salmonella typhimurium and Escherichia coli. RA Esberg B, Leung HC, Tsui HC, Bjork GR, Winkler ME. RL J Bacteriol. 1999 Dec;181(23):7256-65. RN [2] RM PMID: 11882645 RT Enzymatic modification of tRNAs: MiaB is an iron-sulfur protein. RA Pierrel F, Bjork GR, Fontecave M, Atta M. RL J Biol Chem. 2002 Apr 19;277(16):13367-70. RN [3] RM PMID: 11313137 RT TRAM, a predicted RNA-binding domain, common to tRNA uracil methylation and adenine thiolation enzymes. RA Anantharaman V, Koonin EV, Aravind L. RL FEMS Microbiol Lett. 2001 Apr 13;197(2):215-21. A2 hmmalign SE TIGR