The Alcaligenes eutrophus H16 hoxX gene participates in hydrogenase regulation.
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.
Lenz
O
O
Institut für Pflanzenphysiologie und Mikrobiologie, Freien Universität Berlin, Germany.
Schwartz
E
E
Dernedde
J
J
Eitinger
M
M
Friedrich
B
B
D000421:Alcaligenes / Q000201:enzymology / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D018398:Homeodomain Proteins; D006864:Hydrogenase / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016366:Open Reading Frames; D010957:Plasmids; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D018398:Homeodomain Proteins; C088143:HoxX protein, Alcaligenes eutrophus; D015534:Trans-Activators; D014157:Transcription Factors; C088144:HoxA protein; D006864:Hydrogenase