The mRNA derived MalH sRNA contributes to alternative carbon source utilization by tuning maltoporin expression in E. coli
Related Experiment Video
Updated: Dec 6, 2025
In Vivo Monitoring of Transcriptional Activity During Metabolic Transition Using a Bioluminescent Reporter in Yeast
Published on: February 21, 2025
Ira A Iosub1, Marta Marchioretto2, Rob W van Nues3
1Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh0, UK.
Abstract:
Previous high-throughput studies in Gram-negative bacteria identified a large number of 3'UTR fragments that potentially function as sRNAs. Here we extensively characterize the MalH sRNA. We show that MalH is a stable degradation intermediate derived from the 3' end of malG, which is part of the maltose uptake operon transcript malEFG. Unlike the majority of bacterial sRNAs, MalH is transiently expressed during the transition from the exponential to the stationary growth phase, suggesting that it contributes to adaptation to changes in nutrient availability. Over-expression of MalH reduces expression of general outer membrane porins and MicA, a repressor of the high-affinity maltose/maltodextrin transporter LamB. Disrupting MalH production and function significantly reduces lamB accumulation when maltose is the only available carbon source, presumably due to the accumulation of the MicA repressor. We propose that MalH is part of a regulatory network that, during the transition phase, directly or indirectly promotes accumulation of high-affinity maltose transporters in the outer membrane by dampening competing pathways.
Insights
MalH, a novel bacterial small RNA (sRNA), regulates maltose transporter expression during nutrient shifts. This sRNA plays a key role in bacterial adaptation by influencing outer membrane protein levels.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- High-throughput studies reveal numerous 3'UTR fragments acting as bacterial small RNAs (sRNAs).
- The specific roles and regulation of many identified sRNAs remain largely uncharacterized.
Purpose of the Study:
- To extensively characterize the function and regulation of the MalH sRNA in Gram-negative bacteria.
- To elucidate MalH's role in bacterial adaptation to nutrient availability changes.
Main Methods:
- Characterization of MalH as a degradation intermediate of the malG 3'UTR.
- Analysis of MalH expression during bacterial growth phases.
- Investigating the impact of MalH over-expression and disruption on gene expression, including outer membrane porins, MicA, and LamB.
Main Results:
- MalH is a stable degradation intermediate from the 3' end of malG within the malEFG operon.
- MalH exhibits transient expression during the transition from exponential to stationary growth.
- MalH over-expression decreases general outer membrane porins and MicA, while MalH disruption reduces maltose transporter (LamB) accumulation.
Conclusions:
- MalH acts as a regulatory sRNA involved in bacterial adaptation to nutrient availability.
- MalH contributes to the accumulation of high-affinity maltose transporters by modulating competing pathways.
- This suggests MalH is part of a complex regulatory network influencing nutrient uptake systems.
Related Concept Videos
01:29Translational Regulation
01:23Types of RNA
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
01:23Stringent Response in E. coli
01:56Riboswitches
The aptamer has high specificity for a particular metabolite which allows riboswitches to specifically regulate...
01:25Inducible Operons: lac Operon
01:23Transcriptional Regulation: Riboswitches