Highly Conserved Genetic Factors Regulating bla_NDM Gene Expression

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• New Delhi metallo-beta-lactamase (NDM) is a critical threat to carbapenem antibiotics.
• Understanding the regulation of blaNDM gene expression is essential for developing new treatments.

Purpose of the Study:

• To identify and characterize regulatory elements of the blaNDM gene.
• To investigate the role of these elements in NDM production and carbapenem resistance.

Main Methods:

• Comparative sequence analysis of clinical isolates and database sequences.
• Bioinformatics analysis to identify promoter and transcription factor binding sites.
• Site-directed mutagenesis and gene expression analysis (mRNA and protein).
• Electrophoretic mobility shift assays (EMSA) to confirm protein-DNA interactions.

Main Results:

• A conserved 110 bp sequence upstream of blaNDM, containing a core promoter (PNDM) and binding sites for ArcA and ArgR2, was identified.
• PNDM promoter mutations reduced blaNDM expression by over 90% and restored carbapenem susceptibility.
• Mutations in ArcA and ArgR2 binding sites decreased NDM protein production by 24% and 32.7%, respectively.
• EMSA confirmed ArcA and ArgR2 binding to the identified sites.

Conclusions:

• The conserved 110 bp sequence is crucial for regulating blaNDM gene expression.
• The PNDM promoter and transcription factors ArcA/ArgR2 play significant roles in NDM production.
• This conserved sequence represents a potential target for novel therapeutic strategies against NDM-producing bacteria.