Cai Fei, Heinhorst Sabine, Shively Jessup M, Cannon Gordon C
Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, MS 39406-0001, USA.
Arch Microbiol. 2008 Feb;189(2):141-50. doi: 10.1007/s00203-007-0305-y. Epub 2007 Sep 27.
Carboxysomes are polyhedral microcompartments that sequester the CO(2)-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase in many autotrophic bacteria. Their protein constituents are encoded by a set of tightly clustered genes that are thought to form an operon (the cso operon). This study is the first to systematically address transcriptional regulation of carboxysome protein expression. Quantification of transcript levels derived from the cso operon of Halothiobacillus neapolitanus, the sulfur oxidizer that has emerged as the model organism for carboxysome structural and functional studies, indicated that all cso genes are transcribed, albeit at different levels. Combined with comparative genomic evidence, this study supports the premise that the cso gene cluster constitutes an operon. Characterization of transcript 5'- and 3'-ends and examination of likely regulatory sequences and secondary structure elements within the operon suggested potential strategies by which the vastly different levels of individual carboxysome proteins in the microcompartment could have arisen.
羧酶体是多面体微区室，在许多自养细菌中隔离固定二氧化碳的酶1,5 - 二磷酸核酮糖羧化酶/加氧酶。它们的蛋白质成分由一组紧密聚集的基因编码，这些基因被认为形成一个操纵子（cso操纵子）。本研究首次系统地探讨了羧酶体蛋白表达的转录调控。对那不勒斯嗜盐硫杆菌cso操纵子转录本水平的定量分析表明，所有cso基因都被转录，尽管转录水平不同。那不勒斯嗜盐硫杆菌是一种硫氧化菌，已成为羧酶体结构和功能研究的模式生物。结合比较基因组学证据，本研究支持cso基因簇构成一个操纵子的前提。对转录本5'端和3'端的表征以及对操纵子内可能的调控序列和二级结构元件的研究，提出了微区室中单个羧酶体蛋白水平差异巨大可能产生的潜在策略。
