Characterization of multiple promoters and transcript stability in the sacB-sacC gene cluster in Zymomonas mobilis.
In Zymomonas mobilis, the extracellular levansucrase (SacB) and extracellular sucrase (SacC) are involved in sucrose hydrolysis. Genes coding for these two enzymes (sacB and sacC) are arranged in a cluster in the genome and separated by a short intervening sequence. The level of sacC transcript was 12-fold higher than that of sacB transcript. On the other hand, transcript stability analysis in sucrose grown cultures revealed that the half-life of the sacB transcripts (153 s) was more than twofold higher than that of sacC transcript (66 s). The decay curves of sacB and sacC transcripts analyzed by the semi-quantitative RT-PCR correlated well with the decay curves of the respective enzyme activities. In the sacB promoter disruption mutant, Z. moblis BT2, the extracellular sucrase activity decreased from 2.6 to 2.0 U mg(-1) in sucrose medium due to the loss of SacB expression. The expression of sacC in the absence of the sacB promoter suggested that these two genes could be transcribed as different mRNAs. The promoter-lacZ fusion studies in Escherichia coli proved that the short intervening region acts as a strong promoter for the sacC gene.
Department of Genetics, Center for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai, India.
V
V
Senthilkumar
J
J
Rajendhran
S J W
SJ
Busby
P
P
Gunasekaran
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006602:Hexosyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D012329:RNA, Bacterial / Q000378:metabolism; D013393:Sucrase / Q000235:genetics* / Q000378:metabolism; D017355:Zymomonas / Q000201:enzymology / Q000235:genetics*
D001426:Bacterial Proteins; D012329:RNA, Bacterial; D006602:Hexosyltransferases; C021513:levansucrase; D013393:Sucrase