Escherichia coli rna gene encoding RNase I: cloning, overexpression, subcellular distribution of the enzyme, and use of an rna deletion to identify additional RNases.
The cloning and overexpression of the Escherichia coli rna gene encoding RNase I are described. Only a single copy of the rna gene is present on the E. coli chromosome. Although cells with as much as a 100-fold increase in RNase I activity were constructed, little effect on cell growth was observed. Overexpressed RNase I was found in the periplasmic space to the same degree (approximately 85%) as wild-type enzyme, suggesting no limitation in RNase I transport. The rna clone was used to identify a deletion strain totally lacking the rna gene. The normal growth of this strain showed that RNase I is not essential for cell viability. Extracts from the RNase I deletion strain still retained a low level of RNase activity in the presence of EDTA, conclusively demonstrating the existence of additional EDTA-active RNases in E. coli. The possibility of a RNase I inhibitor is also discussed.
Zhu
L Q
LQ
Department of Biochemistry, University of Connecticut Health Center, Farmington 06032.
Gangopadhyay
T
T
Padmanabha
K P
KP
Deutscher
M P
MP
D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D015870:Gene Expression; D005798:Genes, Bacterial; D012259:Ribonuclease, Pancreatic / Q000032:analysis / Q000235:genetics*
D012259:Ribonuclease, Pancreatic