Presence of NADP⁺-specific glyceraldehyde-3-phosphate dehydrogenase and CcpA-dependent transcription of its gene in the ruminal bacteriumStreptococcus bovis

Abstract

To know the role of NADP+-specific glyceraldehyde-3-phosphate dehydrogenase (GAPN) in Streptococcus bovis, the molecular properties and transcriptional control of the gene encoding GAPN (gapN) were examined. The GAPN in S. bovis was deduced to consist of 476 amino acids with a molecular mass of 51.1 kDa. The gapN gene was transcribed in a monocistronic fashion. GAPN synthesis appeared to be regulated at the transcriptional level in response to changes in growth conditions. In a mutant that lacks the ccpA gene encoding catabolite control protein A (CcpA), the gapN-mRNA level was lower than in the parent strain. A binding site of CcpA was found in the upper region of gapN. These results suggest that transcription of gapN is regulated through CcpA. Overexpression of GAPN in S. bovis did not affect the growth rate or formate-to-lactate ratio, suggesting that the flux in the glycolytic pathway is unlikely to be altered by GAPN activity. Streptococcus bovis GAPN was NADP+ dependent, but not phosphate dependent. In addition, S. bovis did not have other NADPH-producing systems such as the hexose monophosphate pathway and NADPH:NAD+ oxidoreductase. Therefore, GAPN may play an important role in NADPH production in S. bovis.

KOMODO: a web tool for detecting and visualizing biased distribution of groups of homologous genes in monophyletic taxa

“…The ENT group, on the other hand, possessed no such bias (Supplementary File 1, Supplementary Figure S2). Together, our findings suggest that the LAB group uses the bypass step observed in glycolysis to produce NADPH, a phenotype already suggested by in vivo studies (13). …”

Molecular characterization and significance of phosphoenolpyruvate carboxykinase in a ruminal bacterium, Streptococcus bovis

“…2). Thus, transcription of the pck operon may be regulated through CcpA, which is similar to the previous results demonstrating that pfl transcription was suppressed by CcpA, whereas transcription of ldh and gapN was enhanced by CcpA (Asanuma and Hino, 2006;Asanuma et al, 2004). CcpA expression was much lower when cells were grown on lactose than when grown on glucose (Asanuma et al, 2004), which is consistent with the result showing that the level of pck transcript in lactose-grown cells was Shown is the ethidium bromide-stained 1% agarose gel of the products obtained with primers designed for the region between gapN and pck (lanes 1 to 3), pck internal region (lanes 4 to 6), or between pck and the downstream region (lanes 7 to 9).…”

“…NC_ 009785), Lactobacillus plantarum WCFS1 (NC_004567), Lactobacillus casei BL23 (NC_010999), and Enterococcus faecium DO (NZ_AAAK03000006), were used to amplify a portion of the S. bovis pck. To sequence the regions upstream and downstream from the amplifi ed pck internal region, nested PCR was carried out on a S. bovis genomic library (Asanuma and Hino, 2006).…”

Sucrose metabolism contributes to in vivo fitness of Streptococcus pneumoniae

“…The LacI/GalR family are well‐studied transcriptional repressors that typically mediate inducible regulation of operons involved in carbon metabolism (Weickert and Adhya, 1992). One example of this family, CcpA (Catabolite control protein A), first discovered as a repressor of the Bacillus subtilis amylase operon (Henkin et al ., 1991), has since been shown to be vital to the co‐ordinated expression of a variety of carbon utilization operons, including the processes of carbon catabolite repression and activation in Gram‐positive bacteria (Luesink et al ., 1998; Stulke and Hillen, 2000; Kim et al ., 2002; Viana et al ., 2005) including streptococci (Simpson and Russell, 1998; Rogers and Scannapieco, 2001; Asanuma and Hino, 2006). In previous studies, it was established that the S. pneumoniae CcpA orthologue contributes to the ability of this pathogen to colonize the mouse nasopharynx and infect the lung (Iyer et al ., 2005) and bloodstream (Iyer et al ., 2005).…”