A comprehensive survey on isoleucine biosynthesis pathways in seven epidemicLeptospira interrogansreference strains of China

Abstract

Previous studies have indicated that different species of Leptospira synthesize isoleucine via either pyruvate and/or threonine pathways. Seven epidemic Leptospira interrogans reference strains from China belonging to different serovars, together with three saprophytic strains of Leptospira biflexa and Leptospira meyeri, were analysed. The isoleucine biosynthesis properties were studied firstly by measuring the key enzymes of the two pathways, citramalate synthase (CimA, CE4.1.3.-) and threonine deaminase (IlvA, CE4.2.1.16), from cell extracts of the bacteria. Meanwhile, alpha-isopropylmalate synthase (LeuA, CE4.2.1.12), the key enzyme of leucine biosynthesis, was also measured as a control. It was found that all L. interrogans strains synthesized isoleucine via the pyruvate pathway exclusively, but L. biflexa and L. meyeri used both pathways. Dot-Blot and PCR amplification of both cimA and ilvA genes in the corresponding strains provided additional evidence consistent with the data of enzymatic assays. Although it is evident that leptospires' isoleucine biosynthesis may preferentially adapt either to the pyruvate pathway exclusively for pathogens or to the combination of both pyruvate and threonine pathways for saprophytes, broader sampling with careful genomospecies identification is needed for a solid conclusion.

Characterization of genes required for the pathogenicity of Pectobacterium carotovorum subsp. carotovorum Pcc21 in Chinese cabbage

“…Mutants Pcc21-M4 and Pcc21-M20 had transposon insertions in two purine biosynthesis protein genes, bifunctional phosphoribosylaminoimidazole carboxamide formyltransferase/IMP cyclohydrolase and phosphoribosylglycinamine-glycine lygase, respectively (Chatterjee & Sonti, 2005; Dougherty et al , 2006). Pcc21-M14 and Pcc21-M19 had mutations in 2-isopropylmalate synthase and phosphoserine phosphatase, which are involved in the biosynthesis of leucine and serine, respectively (Table 2) (Patte et al , 1999; Wang et al , 2007; Zou et al , 2007). These results suggest that the virulence deficiency of mutants with insertions at five different loci is due to an inability to produce pyrimidine, purine, leucine or serine.…”

Enzymology and Evolution of the Pyruvate Pathway to 2-Oxobutyrate in Methanocaldococcus jannaschii

“…have both threonine dehydratase and citramalate synthase enzymes (7,46). Although the presence of a CMS in L. interrogans was previously interpreted as evidence for the early divergence of the Leptospiraceae in the bacterial lineage (43), that CMS is more closely related to bacterial homologs in Bacteroides thetaiotaomicron and Flavobacterium johnsoniae than it is the methanogen CMS (data not shown).…”

Characterization of acetyl-CoA and propionyl-CoA carboxylases encoded by <italic>Leptospira interrogans</italic> serovar Lai: an initial biochemical study for leptospiral gluconeogenesis via anaplerotic CO<sub>2</sub> assimilation

“…1(B)]. Although LA_3803 gene is located on the genome far away from the LA_2736-LA_2735 cistron, and must be transcribed independently, these three genes are likely expressed at the same level (Table 1) if the expression data of whole genome transcriptome and proteome were considered in combination [21,45]. Therefore, we propose that these three genes may encode an acyl-CoA carboxylase holoenzyme composed of the three characteristic single domain subunits [46].…”

“…Basic studies related to the biology of Leptospira have mainly focused on potential virulence factors such as lipopolysaccharide [3][4][5][6][7], dynamics of motility [8][9][10][11][12], and outer-membrane proteins [13][14][15][16][17][18][19][20]. However, the study of its metabolism has been largely limited to those special or unique for the spirochetes, such as the biosynthesis of branch-chain amino acids [21][22][23] and the metabolism of lipids [20,24,25].…”

“…The apparent K m value against acetyl-CoA RT-PCR analysis of the five genes; BC, the operon comprise of pccB and pccC; PB, the operon of accP and accB; C, accC; 2, negative control, RNA as template; þ, positive control, genome as template. is 4.6 + 0.5 mM, with a k cat of 0.66 + 0.03 S 21 . This substrate preference confirmed that the holoenzyme is a PCC.…”