title: Comparative genomic analysis of T-box regulatory systems in bacteria.
abstract: T-box antitermination is one of the main mechanisms of regulation of genes involved in amino acid metabolism in Gram-positive bacteria. T-box regulatory sites consist of conserved sequence and RNA secondary structure elements. Using a set of known T-box sites, we constructed the common pattern and used it to scan available bacterial genomes. New T-boxes were found in various Gram-positive bacteria, some Gram-negative bacteria (delta-proteobacteria), and some other bacterial groups (Deinococcales/Thermales, Chloroflexi, Dictyoglomi). The majority of T-box-regulated genes encode aminoacyl-tRNA synthetases. Two other groups of T-box-regulated genes are amino acid biosynthetic genes and transporters, as well as genes with unknown function. Analysis of candidate T-box sites resulted in new functional annotations. We assigned the amino acid specificity to a large number of candidate amino acid transporters and a possible function to amino acid biosynthesis genes. We then studied the evolution of the T-boxes. Analysis of the constructed phylogenetic trees demonstrated that in addition to the normal evolution consistent with the evolution of regulated genes, T-boxes may be duplicated, transferred to other genes, and change specificity. We observed several cases of recent T-box regulon expansion following the loss of a previously existing regulatory system, in particular, arginine regulon in Clostridium difficile and methionine regulon in Lactobacillaceae. Finally, we described a new structural class of T-boxes containing duplicated terminator-antiterminator elements and unusual reduced T-boxes regulating initiation of translation in the Actinobacteria.
authors: Institute for Information Transmission Problems (The Kharkevich Institute), Russian Academy of Sciences, Moscow 127994, Russia. l_veter@mail.ru
authors: Alexey G
authors: AG
authors: Vitreschak
authors: Andrei A
authors: AA
authors: Mironov
authors: Vassily A
authors: VA
authors: Lyubetsky
authors: Mikhail S
authors: MS
authors: Gelfand
mesh_terms: D020121:5' Untranslated Regions; D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D001419:Bacteria / Q000235:genetics* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D023281:Genomics; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D018085:Regulon; D012689:Sequence Homology, Nucleic Acid; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D020121:5' Untranslated Regions; D026905:Amino Acid Transport Systems; D000596:Amino Acids; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; D020825:T-Box Domain Proteins