Related Experiment Video
Updated: Jan 25, 2026
Purification of a High Molecular Mass Protein in Streptococcus mutans
Published on: September 14, 2019
Membrane proteomic analysis reveals overlapping and independent functions of Streptococcus mutans Ffh, YidC1, and
Surabhi Mishra1, Paula J Crowley1, Katherine R Wright2
1Department of Oral Biology, University of Florida, Gainesville, Florida.
Abstract:
A comparative proteomic analysis was utilized to evaluate similarities and differences in membrane samples derived from the cariogenic bacterium Streptococcus mutans, including the wild-type strain and four mutants devoid of protein translocation machinery components, specifically ∆ffh, ∆yidC1, ∆yidC2, or ∆ffh/yidC1. The purpose of this work was to determine the extent to which the encoded proteins operate individually or in concert with one another and to identify the potential substrates of the respective pathways. Ffh is the principal protein component of the signal recognition particle (SRP), while yidC1 and yidC2 are dual paralogs encoding members of the YidC/Oxa/Alb family of membrane-localized chaperone insertases. Our results suggest that the co-translational SRP pathway works in concert with either YidC1 or YidC2 specifically, or with no preference for paralog, in the insertion of most membrane-localized substrates. A few instances were identified in which the SRP pathway alone, or one of the YidCs alone, appeared to be most relevant. These data shed light on underlying reasons for differing phenotypic consequences of ffh, yidC1 or yidC2 deletion. Our data further suggest that many membrane proteins present in a ∆yidC2 background may be non-functional, that ∆yidC1 is better able to adapt physiologically to the loss of this paralog, that shared phenotypic properties of ∆ffh and ∆yidC2 mutants can stem from impacts on different proteins, and that independent binding to ribosomal proteins is not a primary functional activity of YidC2. Lastly, genomic mutations accumulate in a ∆yidC2 background coincident with phenotypic reversion, including an apparent W138R suppressor mutation within yidC1.
Insights
The signal recognition particle (SRP) pathway collaborates with YidC1 or YidC2 insertases for most membrane protein insertion in Streptococcus mutans, revealing insights into bacterial protein transport and mutant phenotypes.
Area of Science:
- Molecular Biology
- Bacterial Physiology
- Membrane Protein Biogenesis
Background:
- Streptococcus mutans is a cariogenic bacterium with complex protein translocation machinery.
- Ffh (signal recognition particle protein) and YidC1/YidC2 (chaperone insertases) are key components involved in membrane protein insertion.
- Understanding their individual and cooperative roles is crucial for elucidating bacterial membrane biogenesis.
Purpose of the Study:
- To comparatively analyze membrane proteomes of wild-type and mutant Streptococcus mutans strains lacking Ffh, YidC1, YidC2, or both Ffh and YidC1.
- To determine the functional interplay between the SRP pathway and YidC insertases in membrane protein targeting and insertion.
- To identify potential substrates and functional consequences of disrupting these protein translocation pathways.
Main Methods:
- Comparative proteomic analysis of membrane samples from wild-type and mutant Streptococcus mutans strains.
- Utilized strains with deletions in key protein translocation components: ∆ffh, ∆yidC1, ∆yidC2, and ∆ffh/yidC1.
- Investigated the roles of Ffh (SRP component) and YidC1/YidC2 (chaperone insertases) in membrane protein biogenesis.
Main Results:
- The co-translational SRP pathway collaborates with YidC1 or YidC2, or shows no paralog preference, for inserting most membrane proteins.
- Identified instances where the SRP pathway or individual YidC proteins function independently.
- Observed that ∆yidC2 mutants may have non-functional membrane proteins, while ∆yidC1 exhibits better physiological adaptation; suppressor mutations in yidC1 were noted in ∆yidC2 backgrounds.
Conclusions:
- The SRP pathway and YidC insertases (YidC1/YidC2) work in concert for efficient membrane protein insertion in Streptococcus mutans.
- Distinct roles and compensatory mechanisms exist for YidC1 and YidC2, influencing bacterial adaptation and survival.
- These findings provide insights into the molecular basis of differential phenotypic outcomes in translocation mutants and potential therapeutic targets.
Related Concept Videos
01:21Introduction to Test of Independence
The test statistic for a test of independence is similar to that of a goodness-of-fit test:
01:16Hypothesis Test for Test of Independence
H0: The two variables (factors)...
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
00:59Model-Independent Approaches for Pharmacokinetic Data: Noncompartmental Analysis
One important characteristic of noncompartmental analyses is that drug exposure increases proportionally with increasing doses. This...
02:03Law of Independent Assortment
01:14Analysis Methods of Pharmacokinetic Data: Model and Model-Independent Approaches
The model approach uses mathematical models to describe changes in drug concentration over time. Pharmacokinetic models help characterize drug behavior in patients, predict drug concentration in the body fluids, calculate optimum dosage regimens, and evaluate the risk of toxicity. However, ensuring that the model fits the experimental data accurately...