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1etl

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{{STRUCTURE_1etl| PDB=1etl | SCENE= }}
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'''STRUCTURAL CHARACTERISTICS FOR BIOLOGICAL ACTIVITY OF HEAT-STABLE ENTEROTOXIN PRODUCED BY ENTEROTOXIGENIC ESCHERICHIA COLI: X-RAY CRYSTALLOGRAPHY OF WEAKLY TOXIC AND NONTOXIC ANALOGS'''
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===STRUCTURAL CHARACTERISTICS FOR BIOLOGICAL ACTIVITY OF HEAT-STABLE ENTEROTOXIN PRODUCED BY ENTEROTOXIGENIC ESCHERICHIA COLI: X-RAY CRYSTALLOGRAPHY OF WEAKLY TOXIC AND NONTOXIC ANALOGS===
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==Overview==
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Heat-stable enterotoxin (ST) produced by a pathogenic strain of Escherichia coli exerts its function by binding to a membrane-bound guanylyl cyclase on intestinal epithelial cell membranes, which in turn catalyzes the production of cyclic GMP as a second messenger in the cells. To elucidate the structural requirements for the biological activities of ST, we synthesized [Mpr5,Gly13]STp(5-17) and [Mpr5,Leu13]STp(5-17), which are weakly toxic and nontoxic analogs of STp, in which the toxic domain consists of the sequence from Cys at position 5 to Cys at position 17. In these analogs, Cys at position 5 is replaced by Mpr (beta-mercaptopropionic acid) and Ala at position 13 by Gly and Leu, respectively. We examined these analogs by X-ray diffraction analysis using direct methods and refined the structures to crystallographic R factors of 7.3% and 6.6% using 5492 and 5122 data, respectively, observed &gt; 3 sigma (Fo) with a resolution of 0.89 A. These peptides have a right-handed spiral structure consisting of three structural segments: an N-terminal 3(10) helix, a central type I beta-turn, and a C-terminal type II beta-turn. These structures show minor differences from that of [Mpr5]STp(5-17), the fully toxic analog of heat-stable enterotoxin [Ozaki et al. (1991) J. Biol. Chem. 266, 5934-5941], suggesting that the decrease and loss of the biological activities of [Mpr5,Gly13]STp(5-17) and [Mpr5,Leu13]STp(5-17), respectively, are not caused by structural changes but are associated with the direct interaction of Ala13 with the receptor protein. Careful comparison of these structures in crystalline states revealed that ST has the following structural characteristics: (i) inherent flexibility at the junctions of the three segments and in the central segment, which includes the putative receptor-binding residues, Ala13, (ii) a specific hydrophobic character around the central segment, and (iii) an unexpected C-terminal folding similar to those of functionally unrelated peptides that are known to be ionophores.
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(as it appears on PubMed at http://www.pubmed.gov), where 8038153 is the PubMed ID number.
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{{ABSTRACT_PUBMED_8038153}}
==About this Structure==
==About this Structure==
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[[Category: Shimonishi, Y.]]
[[Category: Shimonishi, Y.]]
[[Category: Enterotoxin]]
[[Category: Enterotoxin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 01:57:43 2008''

Revision as of 22:57, 30 June 2008

Image:1etl.png

Template:STRUCTURE 1etl

STRUCTURAL CHARACTERISTICS FOR BIOLOGICAL ACTIVITY OF HEAT-STABLE ENTEROTOXIN PRODUCED BY ENTEROTOXIGENIC ESCHERICHIA COLI: X-RAY CRYSTALLOGRAPHY OF WEAKLY TOXIC AND NONTOXIC ANALOGS

Template:ABSTRACT PUBMED 8038153

About this Structure

1ETL is a Single protein structure. Full crystallographic information is available from OCA.

Reference

Structural characteristics for biological activity of heat-stable enterotoxin produced by enterotoxigenic Escherichia coli: X-ray crystallography of weakly toxic and nontoxic analogs., Sato T, Ozaki H, Hata Y, Kitagawa Y, Katsube Y, Shimonishi Y, Biochemistry. 1994 Jul 26;33(29):8641-50. PMID:8038153

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