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Title:Structure, function, and evolution of proline transport systems in Salmonella typhimurium
Author(s):Liao, Min-Ken
Doctoral Committee Chair(s):Maloy, Stanley R.
Department / Program:Microbiology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Molecular
Biology, Microbiology
Abstract:Solute transport is an essential and often the rate-limiting step in metabolism and energy utilization. Nutrient uptake across the cytoplasmic membrane is mediated by integral membrane proteins called permeases. The goal of this research was to understand the structure and function of the substrate binding site of proline permease and the evolution of a new proline transport system.
To identify the proline binding site of proline permease, we isolated a large number of rare putP missense mutations that alter the kinetics and specificity of transport. To study the domain-domain interaction, more than 100 second-site mutations which restore the activity of proline transport were isolated. The DNA sequence of several of the mutants and revertants were determined.
To identify the physical constraint on the proline binding site of proline permease, a set of proline analogs were studied. If the modification in the analog prevents its transport, the position of the modification is critical for substrate recognition by proline permease. If the modification does not affect its transport, the position of the modification is not critical for recognition. The $K\sb{i}$ values of the analogs which competitively inhibit proline transport were determined. Based on these studies, a docking model for the binding site was proposed.
To learn how a new transport system evolves, a cryptic proline transport system was studied. The structural gene of the new proline transport system designated proY located at 8 min of chromosomal linkage map. Activity of proY is modulated by the proZ gene located at 76.5 min of the linkage map. Both proY and proZ are closely linked to branched-chain amino acid transport systems, LIV-I and LIV-II. The proZ and proY interact in protein level.
Issue Date:1994
Rights Information:Copyright 1994 Liao, Min-Ken
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9416394
OCLC Identifier:(UMI)AAI9416394

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