Leach F, Wacks D B, Signer E R
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Gene. 1994 Oct 11;148(1):87-90. doi: 10.1016/0378-1119(94)90238-0.
The pectate-lyase-encoding gene pelB of Erwinia chrysanthemi Ec16 was used as a probe for hybridization to Rhizobium meliloti Rm1021 chromosomal DNA under low-stringency conditions. An Rm1021 DNA fragment that hybridized to this probe was cloned and sequenced. Results of RNA hybridization indicate that a portion of the cloned fragment is transcribed in R. meliloti. Although the Rm1021 fragment shares no significant nucleotide sequence identity with Ec16 pelB, it includes an ORF (open reading frame) that shares a high degree of nt sequence identity with the Escherichia coli murD gene. This gene codes for UDP-N-acetylmuramoyl-L-alanyl-D-glutamate synthetase, which catalyzes a step in the synthesis of the E. coli cell wall. The R. meliloti putative murD sequence is preceded by a partial ORF that shares sequence identity with mraY. The orientation of the two ORFs in R. meliloti is similar to that of the E. coli murD and mraY genes.
菊欧文氏菌Ec16的果胶酸裂解酶编码基因pelB被用作探针，在低严谨条件下与苜蓿根瘤菌Rm1021染色体DNA进行杂交。克隆并测序了与该探针杂交的Rm1021 DNA片段。RNA杂交结果表明，克隆片段的一部分在苜蓿根瘤菌中被转录。尽管Rm1021片段与Ec16 pelB没有显著的核苷酸序列同一性，但它包含一个与大肠杆菌murD基因具有高度核苷酸序列同一性的开放阅读框（ORF）。该基因编码UDP-N-乙酰胞壁酰-L-丙氨酰-D-谷氨酸合成酶，它催化大肠杆菌细胞壁合成中的一个步骤。苜蓿根瘤菌推定的murD序列之前有一个与mraY具有序列同一性的部分ORF。苜蓿根瘤菌中这两个ORF的方向与大肠杆菌murD和mraY基因的方向相似。
