Expression and regulation of protein K, an Escherichia coli K1 porin, in Escherichia coli K-12

✍ Scribed by Joyce A. Sutcliffe; John D. Foulds

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 576 KB
• Volume: 23
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240230108

✦ Synopsis

Using a modified lambda phage as a vector and a procedure developed in Dr. C. Schnaitman's laboratory, we have cloned the structural gene for protein K from an Escherichia coli K1 strain to an E coli K-12 strain. The cloned inserts consist of two HindIII fragments, 4 kb and 6.5 kb in size. The protein produced by the insert is nearly identical to "authentic" protein K when chymotryptic peptides of 125I-labeled proteins are compared. Protein K was found to respond to changes in the osmolarity of the medium, being favored in trypticase soy broth (high osmolarity). This fluctuation was not dependent on a functional ompR gene. However, protein K was not expressed in strains carrying the envZ-473 mutation. Thus, protein K appears to be within a class of exported proteins whose expression is regulated by the envZ gene independent of the ompR gene.