skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability

Abstract

Eukaryotic thrombospondin type 3 repeat (TT3R) is an efficient calcium ion (Ca2+) binding motif only found in mammalian thrombospondin family. TT3R has also been found in prokaryotic cellulase Cel5G, which was thought to forfeit the Ca2+-binding capability due to the formation of intra-repeat disulfide bonds, instead of the inter-repeat ones possessed by eukaryotic TT3Rs. In this study, we have identified an enormous number of prokaryotic TT3R-containing proteins belonging to several different protein families, including outer membrane protein A (OmpA), an important structural protein connecting the outer membrane and the periplasmic peptidoglycan layer in gram-negative bacteria. Here, we report the crystal structure of the periplasmic region of OmpA from Capnocytophaga gingivalis, which contains a linker region comprising five consecutive TT3Rs. The structure of OmpA-TT3R exhibits a well-ordered architecture organized around two tightly-coordinated Ca2+ and confirms the presence of abnormal intra-repeat disulfide bonds. Further mutagenesis studies showed that the Ca2+-binding capability of OmpA-TT3R is indeed dependent on the proper formation of intra-repeat disulfide bonds, which help to fix a conserved glycine residue at its proper position for Ca2+ coordination. Additionally, despite lacking inter repeat disulfide bonds, the interfaces between adjacent OmpA-TT3Rs are enhanced by both hydrophobic and conserved aromatic-proline interactions.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
National Natural Science Foundation of China (NNSFC); Chinese Academy of Sciences (CAS) - Strategic Priority Research Program
OSTI Identifier:
1394814
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cell Calcium (Scotland); Journal Volume: 66
Country of Publication:
United States
Language:
English
Subject:
Aromatic-proline interaction; CH/pi interaction; Calcium-binding motif; OMpA; TSP3 repeat

Citation Formats

Dai, Shuyan, Sun, Cancan, Tan, Kemin, Ye, Sheng, and Zhang, Rongguang. Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability. United States: N. p., 2017. Web. doi:10.1016/j.ceca.2017.05.016.
Dai, Shuyan, Sun, Cancan, Tan, Kemin, Ye, Sheng, & Zhang, Rongguang. Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability. United States. doi:10.1016/j.ceca.2017.05.016.
Dai, Shuyan, Sun, Cancan, Tan, Kemin, Ye, Sheng, and Zhang, Rongguang. Fri . "Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability". United States. doi:10.1016/j.ceca.2017.05.016.
@article{osti_1394814,
title = {Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability},
author = {Dai, Shuyan and Sun, Cancan and Tan, Kemin and Ye, Sheng and Zhang, Rongguang},
abstractNote = {Eukaryotic thrombospondin type 3 repeat (TT3R) is an efficient calcium ion (Ca2+) binding motif only found in mammalian thrombospondin family. TT3R has also been found in prokaryotic cellulase Cel5G, which was thought to forfeit the Ca2+-binding capability due to the formation of intra-repeat disulfide bonds, instead of the inter-repeat ones possessed by eukaryotic TT3Rs. In this study, we have identified an enormous number of prokaryotic TT3R-containing proteins belonging to several different protein families, including outer membrane protein A (OmpA), an important structural protein connecting the outer membrane and the periplasmic peptidoglycan layer in gram-negative bacteria. Here, we report the crystal structure of the periplasmic region of OmpA from Capnocytophaga gingivalis, which contains a linker region comprising five consecutive TT3Rs. The structure of OmpA-TT3R exhibits a well-ordered architecture organized around two tightly-coordinated Ca2+ and confirms the presence of abnormal intra-repeat disulfide bonds. Further mutagenesis studies showed that the Ca2+-binding capability of OmpA-TT3R is indeed dependent on the proper formation of intra-repeat disulfide bonds, which help to fix a conserved glycine residue at its proper position for Ca2+ coordination. Additionally, despite lacking inter repeat disulfide bonds, the interfaces between adjacent OmpA-TT3Rs are enhanced by both hydrophobic and conserved aromatic-proline interactions.},
doi = {10.1016/j.ceca.2017.05.016},
journal = {Cell Calcium (Scotland)},
number = ,
volume = 66,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 2017},
month = {Fri Sep 01 00:00:00 EDT 2017}
}