To study the effect of ntrC gene product on the expression and regulation of other important nitrogen-fixing genes in Alcaligenes faecalis, partially nfrC-deleted mutants of A. faecalis have been generated. To start w...To study the effect of ntrC gene product on the expression and regulation of other important nitrogen-fixing genes in Alcaligenes faecalis, partially nfrC-deleted mutants of A. faecalis have been generated. To start with, the ntrC gene of A. faecalis was cloned into a suicide plasmid pSUP202 to create a recombinant plasmid pSUML The nfrCgene in pSUM1 was then replaced by a /acZ-Kmr fragment resulted in the generation of a plasmid pSUM2. The lacZfragment in pSUM2 was further removed and a plasmid pSUMS produced. As a second step, the plasmid pSUM2 or pSUM3 was introduced into the wild type of A. faecalis A1501 by conjugation and two partially nfrC-deleted mutants A15CM1 (ntrC:: lacZ) and A15CM2 (ntrC-) were obtained. To understand the regulatory effect of the NtrC on the expression of nifH and nifA, a nifH-lacZ gene or a nifA-lacZ gene was introduced into the ntrC- mutant by conjugation. The results indicated that: (i) although the ntrC - mutant was nif +, its nitrogen fixation activity was only 20%展开更多
文摘To study the effect of ntrC gene product on the expression and regulation of other important nitrogen-fixing genes in Alcaligenes faecalis, partially nfrC-deleted mutants of A. faecalis have been generated. To start with, the ntrC gene of A. faecalis was cloned into a suicide plasmid pSUP202 to create a recombinant plasmid pSUML The nfrCgene in pSUM1 was then replaced by a /acZ-Kmr fragment resulted in the generation of a plasmid pSUM2. The lacZfragment in pSUM2 was further removed and a plasmid pSUMS produced. As a second step, the plasmid pSUM2 or pSUM3 was introduced into the wild type of A. faecalis A1501 by conjugation and two partially nfrC-deleted mutants A15CM1 (ntrC:: lacZ) and A15CM2 (ntrC-) were obtained. To understand the regulatory effect of the NtrC on the expression of nifH and nifA, a nifH-lacZ gene or a nifA-lacZ gene was introduced into the ntrC- mutant by conjugation. The results indicated that: (i) although the ntrC - mutant was nif +, its nitrogen fixation activity was only 20%
