Presence of NADP+-specific glyceraldehyde-3-phosphate dehydrogenase and CcpA-dependent transcription of its gene in the ruminal bacterium Streptococcus bovis
Presence of NADP+-specific glyceraldehyde-3-phosphate dehydrogenase and CcpA-dependent transcription of its gene in the ruminal bacterium Streptococcus bovis
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DOI：
10.1111/j.1574-6968.2006.00111.x
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发表时间：
2006-04-01
影响因子：
2.1
通讯作者：
Hino, T
中科院分区：
文献类型：
--
作者：
Asanuma, N;Hino, T
为了了解 NADP(+) 特异性甘油醛-3-磷酸脱氢酶 (GAPN) 在牛链球菌中的作用，检查了编码 GAPN (gapN) 的基因的分子特性和转录控制。推测牛链球菌中的 GAPN 由 476 个氨基酸组成，分子量为 51.1 kDa。 gapN 基因以单顺反子方式转录。 GAPN 合成似乎在转录水平上受到生长条件变化的调节。在缺乏编码分解代谢物控制蛋白 A (CcpA) 的 ccpA 基因的突变体中，gapN-mRNA 水平低于亲本菌株。在gapN 的上部区域发现了CcpA 的结合位点。这些结果表明gapN 的转录是通过CcpA 调节的。牛链球菌中 GAPN 的过度表达不会影响生长速率或甲酸与乳酸的比率，表明糖酵解途径中的通量不太可能被 GAPN 活性改变。牛链球菌 GAPN 具有 NADP(+) 依赖性，但不具有磷酸盐依赖性。此外，牛链球菌不具有其他NADPH产生系统，例如己糖单磷酸途径和NADPH:NAD(+)氧化还原酶。因此，GAPN可能在牛链球菌NADPH生产中发挥重要作用。
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.