Zinc is an unexpected allosteric effector of an engineered maltose-activated β-lactamase

BIOT 86

Jing Liang, JL@JHMI.EDU, Program in Molecular and Computational Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 and Marc Ostermeier, oster@jhu.edu, Department of Chemical and Biomolecular Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218.
We have previously created protein switches by recombining non-homologous genes with the prerequisite input and output functions and subjecting the resulting library to genetic selection and screening. By recombining the genes coding for E. coli maltose binding protein (MBP) and TEM1 β-lactamase (BLA), we have created a family β-lactamases in which maltose modulates the level of β-lactam hydrolysis activity. Unexpectedly, the β-lactamase activity one of these switches (RG13) is specifically inhibited by Zn2+ with a Ki of 4 μM. The inhibition is independent of the presence of maltose and is not the result of protein precipitation. RG13's zinc-binding activity is intriguing since MBP has been shown not to bind Zn2+ and BLA catalytic activity is not affected by the presence of zinc. The nature of the zinc effect and its implications for the evolution of protein function and allostery will be discussed.
 

Biophysical and Biomolecular Symposium: Protein Engineering
8:00 AM-11:00 AM, Monday, 11 September 2006 Hilton San Francisco -- Imperial B Ballroom, Oral

Division of Biochemical Technology

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006