Structural insights into the disulfide isomerase and chaperone activity of TrbB of the F plasmid type IV secretion system

Structural insights into the disulfide isomerase and chaperone activity of TrbB of the F plasmid type IV secretion system

Bacteria have evolved elaborate mechanisms to thrive in stressful environments. F-like plasmids in gram-negative bacteria encode for a multi-protein Type IV Secretion System (T4SSF) that is functional for bacterial proliferation and adaptation through the process of conjugation. The periplasmic prot...

Full description

Saved in:
Bibliographic Details
Published in:Current research in structural biology Vol. 8; p. 100156
Main Authors: Apostol, Arnold J., Bragagnolo, Nicholas J., Rodriguez, Christina S., Audette, Gerald F.
Format: Journal Article
Language:English
Published: Netherlands Elsevier B.V 2024
Subjects:
1H–15N heteronuclear single quantum coherence spectroscopy
Circular dichroism spectroscopy
ColabFold-AlphaFold2
Disulfide isomerase
F-like type IV secretion system
Protein design
Small angle X-Ray scattering
Circular dichroism spectroscopy
SS
aa
F-like type IV secretion system
CD
DI
DTT
CF-AF2
1H–15N heteronuclear single quantum coherence spectroscopy
ColabFold-AlphaFold2
Protein design
Small angle X-Ray scattering
Disulfide isomerase
T4SSF
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Bacteria have evolved elaborate mechanisms to thrive in stressful environments. F-like plasmids in gram-negative bacteria encode for a multi-protein Type IV Secretion System (T4SSF) that is functional for bacterial proliferation and adaptation through the process of conjugation. The periplasmic protein TrbB is believed to have a stabilizing chaperone role in the T4SSF assembly, with TrbB exhibiting disulfide isomerase (DI) activity. In the current report, we demonstrate that the deletion of the disordered N-terminus of TrbBWT, resulting in a truncation construct TrbB37-161, does not affect its catalytic in vitro activity compared to the wild-type protein (p = 0.76). Residues W37–K161, which include the active thioredoxin motif, are sufficient for DI activity. The N-terminus of TrbBWT is disordered as indicated by a structural model of GST-TrbBWT based on ColabFold-AlphaFold2 and Small Angle X-Ray Scattering data and 1H–15N Heteronuclear Single Quantum Correlation (HSQC) spectroscopy of the untagged protein. This disordered region likely contributes to the protein's dynamicity; removal of this region results in a more stable protein based on 1H–15N HSQC and Circular Dichroism Spectroscopies. Lastly, size exclusion chromatography analysis of TrbBWT in the presence of TraW, a T4SSF assembly protein predicted to interact with TrbBWT, does not support the inference of a stable complex forming in vitro. This work advances our understanding of TrbB's structure and function, explores the role of structural disorder in protein dynamics in the context of a T4SSF accessory protein, and highlights the importance of redox-assisted protein folding in the T4SSF. [Display omitted] •TrbB of the F-plasmid Type IV Secretion System functions as a disulfide isomerase.•Predicted models of TrbB highlight regions of increased flexibility.•Structurally, TrbB has a flexible N-terminus and C-terminal thioredoxin domain.•Truncation of TrbB increases stability and facilitates structural analysis.•The C-terminal region of TrbB is sufficient for disulfide isomerase activity.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:2665-928X
2665-928X
DOI:10.1016/j.crstbi.2024.100156