PMID:8831785
| Citation |
Betton, JM, Boscus, D, Missiakas, D, Raina, S and Hofnung, M (1996) Probing the structural role of an alpha beta loop of maltose-binding protein by mutagenesis: heat-shock induction by loop variants of the maltose-binding protein that form periplasmic inclusion bodies. J. Mol. Biol. 262:140-50 |
|---|---|
| Abstract |
The maltose-binding protein (MBP) of Escherichia coli is the periplasmic receptor of the maltose transport system. Previous studies have identified amino acid substitutions in an alpha/beta loop of the structure of MBP that are critical for the in vivo folding. To probe genetically the structural role of this surface loop, we generated a library in which the corresponding codons 32 and 33 of malE were mutagenized. The maltose phenotype, which correlates with a biologically active structure of MBP in the periplasm, indicated a considerable variability in the loop residues compatible with a correct in vivo folding pathway of the protein. By the same genetic screens, we characterized loop-variant MBPs associated with a defective periplasmic folding pathway and aggregated into inclusion bodies. Heat-shock induction with production of misfolded loop variants was examined using both lon-lacZ and htrA-lacZ fusions. We found that the extent of formation of inclusion bodies in the periplasm of E. coli, from misfolded loop variant MBPs, correlated with the level of heat-shock response regulated by the alternate heat-shock sigma factor, sigma 24. |
| Links |
PubMed Online version:10.1006/jmbi.1996.0504 |
| Keywords |
ATP-Binding Cassette Transporters; ATP-Dependent Proteases; Amino Acid Sequence; Bacterial Proteins; Calcium-Binding Proteins; Carrier Proteins/chemistry; Carrier Proteins/genetics; Databases, Factual; Escherichia coli; Escherichia coli Proteins; Heat-Shock Proteins/metabolism; Hot Temperature; Inclusion Bodies/chemistry; Inclusion Bodies/ultrastructure; Lac Operon; Maltose-Binding Proteins; Molecular Sequence Data; Monosaccharide Transport Proteins; Mutagenesis, Site-Directed; Periplasmic Binding Proteins; Periplasmic Proteins; Protease La; Protein Structure, Secondary; Protein Structure, Tertiary; Serine Endopeptidases/metabolism; Structure-Activity Relationship |
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