The C‐terminus is essential for the stability of the mycobacterial channel protein MspA

Outer membrane proteins perform essential functions in uptake and secretion processes in bacteria. MspA is an octameric channel protein in the outer membrane of Mycobacterium smegmatis and is structurally distinct from any other known outer membrane protein. MspA is the founding member of a family w...

Full description

Saved in:
Bibliographic Details
Published in:Protein science Vol. 33; no. 3; pp. e4912 - n/a
Main Authors: Pavlenok, Mikhail, Nair, Rashmi Ravindran, Hendrickson, R. Curtis, Niederweis, Michael
Format: Journal Article
Language:English
Published: Hoboken, USA John Wiley & Sons, Inc 01.03.2024
Wiley Subscription Services, Inc
Subjects:
Assembly
Bacteria
channel
Channel pores
Conserved sequence
electrophysiology
Flow cytometry
Gene deletion
Gram-negative bacteria
Membrane proteins
Membranes
Methionine
Methionine - metabolism
Mutation
Mycobacterium
Mycobacterium smegmatis - genetics
Mycobacterium smegmatis - metabolism
nanopore sequencing
Nanotechnology
Oligomerization
Outer membrane proteins
porin
Porins - chemistry
Porins - genetics
Porins - metabolism
Protein folding
protein stability
Proteins
stochastic sensing
Sulfur
Thermal stability
Tryptophan
Tryptophan - metabolism
channel
nanopore sequencing
stochastic sensing
electrophysiology
protein stability
porin
ISSN:0961-8368, 1469-896X, 1469-896X
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Outer membrane proteins perform essential functions in uptake and secretion processes in bacteria. MspA is an octameric channel protein in the outer membrane of Mycobacterium smegmatis and is structurally distinct from any other known outer membrane protein. MspA is the founding member of a family with more than 3000 homologs and is one of the most widely used proteins in nanotechnological applications due to its advantageous pore structure and extraordinary stability. While a conserved C‐terminal signal sequence is essential for folding and protein assembly in the outer membrane of Gram‐negative bacteria, the molecular determinants of these processes are unknown for MspA. In this study, we show that mutation and deletion of methionine 183 in the highly conserved C‐terminus of MspA and mutation of the conserved tryptophan 40 lead to a complete loss of protein in heat extracts of M. smegmatis. Swapping these residues partially restores the heat stability of MspA indicating that methionine 183 and tryptophan 40 form a conserved sulfur‐π electron interaction, which stabilizes the MspA monomer. Flow cytometry showed that all MspA mutants are surface‐accessible demonstrating that oligomerization and membrane integration in M. smegmatis are not affected. Thus, the conserved C‐terminus of MspA is essential for its thermal stability, but it is not required for protein assembly in its native membrane, indicating that this process is mediated by a mechanism distinct from that in Gram‐negative bacteria. These findings will benefit the rational design of MspA‐like pores to tailor their properties in current and future applications.
Bibliography:Review Editor
Aitziber L. Cortajarena
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 14
content type line 23
Review Editor: Aitziber L. Cortajarena
ISSN:0961-8368
1469-896X
1469-896X
DOI:10.1002/pro.4912