Lenz O, Schwartz E, Dernedde J, Eitinger M, Friedrich B
Institut für Pflanzenphysiologie und Mikrobiologie, Freien Universität Berlin, Germany.
J Bacteriol. 1994 Jul;176(14):4385-93. doi: 10.1128/jb.176.14.4385-4393.1994.
Nucleotide sequence analysis revealed a 1,791-bp open reading frame in the hox gene cluster of the gram-negative chemolithotroph Alcaligenes eutrophus H16. In order to investigate the biological role of this open reading frame, we generated an in-frame deletion allele via a gene replacement strategy. The resulting mutant grew significantly more slowly than the wild type under lithoautotrophic conditions (6.1 versus 4.2 h doubling time). A reduction in the level of the soluble NAD-reducing hydrogenase (60% of the wild-type activity) was shown to be the cause of the slow lithoautotrophic growth. We used plasmid-borne gene fusions to monitor the expression of the operons encoding the soluble and membrane-bound hydrogenases. The expression of both operons was lower in the mutant than in the wild-type strain. These results suggest that the newly identified gene, designated hoxX, encodes a regulatory component which, in conjunction with the transcriptional activator HoxA, controls hydrogenase synthesis.
核苷酸序列分析显示，在革兰氏阴性化能自养菌嗜碱假单胞菌H16的hox基因簇中存在一个1791bp的开放阅读框。为了研究这个开放阅读框的生物学作用，我们通过基因置换策略构建了一个框内缺失等位基因。在自养条件下，所得突变体的生长速度明显慢于野生型（倍增时间分别为6.1小时和4.2小时）。可溶性NAD还原氢化酶水平降低（为野生型活性的60%）被证明是自养生长缓慢的原因。我们使用质粒携带的基因融合来监测编码可溶性和膜结合氢化酶的操纵子的表达。突变体中这两个操纵子的表达均低于野生型菌株。这些结果表明，新鉴定的基因hoxX编码一种调控成分，它与转录激活因子HoxA共同控制氢化酶的合成。
