Ferreira Daniela, Leitão Elsa, Sjöholm Johannes, Oliveira Paulo, Lindblad Peter, Moradas-Ferreira Pedro, Tamagnini Paula
IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
Arch Microbiol. 2007 Dec;188(6):609-17. doi: 10.1007/s00203-007-0281-2. Epub 2007 Jul 17.
Lyngbya majuscula CCAP 1446/4 is a filamentous cyanobacterium possessing both an uptake and a bi-directional hydrogenase. The presence of a single copy of the hyp operon in the cyanobacterial genomes suggests that these accessory genes might be responsible for the maturation of both hydrogenases. We investigated the concomitant transcription of hypFCDEAB with the hydrogenases structural genes--hup and hox. RT-PCRs performed with L. majuscula cells grown under different physiological conditions showed a substantial decrease in the relative amount of hupL transcript under non-N2-fixing conditions. In contrast, no significant differences were observed for the transcript levels of hypFCDEAB in all conditions tested, while minor fluctuations could be discerned for hoxH. Previously, it was demonstrated that the transcriptional regulators NtcA and LexA interact with the promoter regions of hup and hox, respectively, and that putative binding sites for both proteins are present in the hyp promoter of L. majuscula. Therefore, a putative involvement of NtcA and LexA in the regulation of the hyp transcription was investigated. Electrophoretic mobility shift assays resulted in NtcA or LexA-bound retarded fragments, suggesting the involvement of these proteins in the transcriptional regulation of hypFCDEAB.
巨大鞘丝藻CCAP 1446/4是一种丝状蓝细菌，同时拥有摄取型和双向氢化酶。蓝细菌基因组中hyp操纵子的单拷贝存在表明，这些辅助基因可能负责两种氢化酶的成熟。我们研究了hypFCDEAB与氢化酶结构基因hup和hox的伴随转录情况。对在不同生理条件下生长的巨大鞘丝藻细胞进行的逆转录聚合酶链反应（RT-PCR）显示，在非固氮条件下，hupL转录本的相对量大幅下降。相比之下，在所有测试条件下，hypFCDEAB的转录水平均未观察到显著差异，而hoxH的转录水平则有微小波动。此前已证明，转录调节因子NtcA和LexA分别与hup和hox的启动子区域相互作用，并且在巨大鞘丝藻的hyp启动子中存在这两种蛋白质的假定结合位点。因此，研究了NtcA和LexA在hyp转录调控中的假定作用。电泳迁移率变动分析产生了与NtcA或LexA结合的滞后片段，表明这些蛋白质参与了hypFCDEAB的转录调控。
