Tavares Isabel M, Leitão Jorge H, Sá-Correia Isabel
Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
Biochem Biophys Res Commun. 2003 Mar 7;302(2):363-71. doi: 10.1016/s0006-291x(03)00169-4.
A computer-aided analysis of the Pseudomonas aeruginosa PAO1 genome surrounding the glmM gene was carried out and the organization of this chromosomal region was compared with the equivalent regions in other gamma-proteobacteria species with the genome sequence available. glmM encodes the enzyme phosphoglucosamine mutase which catalyses the interconversion of glucosamine-6-phosphate into glucosamine-1-phosphate in the biosynthetic pathway leading to the synthesis of UDP-N-acetylglucosamine which is simultaneously a precursor for the biosynthesis of cell-wall peptidoglycan and outer membrane lipopolysaccharide. Northern blot analysis suggests that glmM may be a part of the five-cistron operonic structure composed by the Escherichia coli homologues ftsJ, ftsH, folP, glmM, and tpiA. The secG gene, downstream tpiA, does not make part of this polygenic organization, being actively transcribed as a monocistronic mRNA during transition to the stationary phase of growth. Differently, transcription of genes in the glmM operon is more active in the early exponential phase, decreasing with the increase of cell density during exponential growth and reaching negligible values in stationary phase cells.
对铜绿假单胞菌PAO1基因组中围绕glmM基因的区域进行了计算机辅助分析，并将该染色体区域的组织与其他具有可用基因组序列的γ-变形菌物种中的等效区域进行了比较。glmM编码磷酸葡糖胺变位酶，该酶在生物合成途径中催化6-磷酸葡糖胺转化为1-磷酸葡糖胺，该途径导致合成UDP-N-乙酰葡糖胺，UDP-N-乙酰葡糖胺同时是细胞壁肽聚糖和外膜脂多糖生物合成的前体。Northern印迹分析表明，glmM可能是由大肠杆菌同源物ftsJ、ftsH、folP、glmM和tpiA组成的五顺反子操纵子结构的一部分。tpiA下游的secG基因不属于这种多基因组织，在生长进入稳定期时作为单顺反子mRNA被积极转录。不同的是，glmM操纵子中的基因转录在指数生长早期更活跃，随着指数生长期细胞密度的增加而降低，在稳定期细胞中达到可忽略不计的值。
