Sauter M, Böhm R, Böck A
Lehrstuhl für Mikrobiologie, Universität München, Germany.
Mol Microbiol. 1992 Jun;6(11):1523-32. doi: 10.1111/j.1365-2958.1992.tb00873.x.
In-frame deletions were introduced into each of the eight genes of the hyc operon coding for products required for the formation of the formate hydrogenlyase (FHL) system. The deletions were transferred to the chromosome and the resulting mutants were analysed for development of formate dehydrogenase H and hydrogenase 1, 2 and 3 activity. It was found that hycA, the promoter-proximal gene, is a regulatory gene and that it codes for a product counteracting transcriptional activation by FhlA. Deletions within the hycB to hycH genes specifically affected formate dehydrogenase H activity or hydrogenase 3 activity, or both. None of the mutations affected hydrogenase 1 or 2 activity. A model is proposed for the functional interaction of the different hyc operon gene products in the formate hydrogenlyase complex, which is based on the results of the mutational analysis, on the determination of the subcellular localization of the FdhF, HycE, HycF and HycG polypeptides and on the similarity of hyc gene product sequences with those from other hydrogenase systems. HycH, the product of the most promoter-distal gene, does not seem to form part of the functional FHL complex but rather is required for the conversion of a precursor form of the large subunit of hydrogenase 3 into the mature form.
移码缺失被引入到甲酸氢化酶（FHL）系统形成所需产物编码的hyc操纵子的八个基因中的每一个。这些缺失被转移到染色体上，并对所得突变体进行甲酸脱氢酶H以及氢化酶1、2和3活性的分析。发现启动子近端基因hycA是一个调控基因，它编码一种对抗FhlA转录激活的产物。hycB至hycH基因内的缺失特异性地影响甲酸脱氢酶H活性或氢化酶3活性，或两者都受影响。没有一个突变影响氢化酶1或2的活性。基于突变分析结果、FdhF、HycE、HycF和HycG多肽亚细胞定位的测定以及hyc基因产物序列与其他氢化酶系统序列的相似性，提出了一个关于不同hyc操纵子基因产物在甲酸氢化酶复合物中功能相互作用的模型。最远端启动子基因的产物HycH似乎并不构成功能性FHL复合物的一部分，而是将氢化酶3大亚基的前体形式转化为成熟形式所必需的。
