Guo D, Tropp B E
Queens College CUNY, Department of Chemistry and Biochemistry, Flushing, NY 11367, USA.
Biochim Biophys Acta. 1998 Jan 5;1389(1):34-42. doi: 10.1016/s0005-2760(97)00086-6.
The gene that codes for cardiolipin (CL) synthase and an adjacent gene that codes for a MecA homolog in the alkaliphilic bacteria Bacillus firmus OF4 have been cloned and sequenced (GenBank accession number U88888). The cls gene contains 1509 nucleotides, corresponding to a polypeptide of 57.9 kDa. The predicted amino acid sequence has 129 identities and 100 similarities with the Escherichia coli CL synthase. Homologies were also noted with polypeptide sequences from putative cls genes from Bacillus subtilis and Pseudomonas putida. Conserved histidine, tyrosine, and serine residues may be part of the active site and participate in phosphatidyl group transfer. The B. firmus OF4 cls gene product was inserted into plasmid pET3 to form a recombinant plasmid pDG2, which overproduces CL synthase in E. coli. A membrane fraction containing the overproduced enzyme converts phosphatidylglycerol to CL and glycerol. The B. firmus enzyme is stimulated by potassium phosphate, inhibited by CL and phosphatidate, and has a slightly higher pH optimum than the E. coli enzyme.
已克隆并测序了嗜碱芽孢杆菌OF4中编码心磷脂（CL）合酶的基因以及一个编码MecA同源物的相邻基因（GenBank登录号U88888）。cls基因包含1509个核苷酸，对应于一个57.9 kDa的多肽。预测的氨基酸序列与大肠杆菌CL合酶有129个相同和100个相似之处。还发现与枯草芽孢杆菌和恶臭假单胞菌推定的cls基因的多肽序列具有同源性。保守的组氨酸、酪氨酸和丝氨酸残基可能是活性位点的一部分，并参与磷脂酰基转移。将嗜碱芽孢杆菌OF4 cls基因产物插入质粒pET3中，形成重组质粒pDG2，该质粒在大肠杆菌中过量产生CL合酶。含有过量产生的酶的膜部分将磷脂酰甘油转化为CL和甘油。嗜碱芽孢杆菌的酶受磷酸钾刺激，受CL和磷脂酸抑制，最适pH值略高于大肠杆菌的酶。
