A Multiplex Enzymatic Machinery for Cellular Protein S-nitrosylation

Area of Science:

• Biochemistry
• Cellular Signaling
• Microbiology

Background:

• S-nitrosylation is a critical post-translational modification involving nitric oxide (NO) and S-nitrosothiols (SNOs).
• It is generally considered a non-enzymatic process, occurring through various chemical pathways.
• This modification impacts diverse protein classes and functions as a fundamental redox-based cellular signaling mechanism.

Purpose of the Study:

• To investigate the enzymatic basis of endogenous protein S-nitrosylation in Escherichia coli (E. coli).
• To elucidate the role of the hybrid cluster protein (Hcp) and nitrate reductase in NO production and S-nitrosylation.
• To understand the broader implications for nitric oxide-based cellular signaling.

Main Methods:

• Utilized E. coli as a model organism.
• Investigated the impact of anaerobiosis on nitrate.
• Analyzed the induction of Hcp and nitrate reductase.
• Characterized the S-nitrosylation-dependent interactome, including NO synthase, SNO synthase, and trans-nitrosylases.

Main Results:

• Demonstrated that endogenous S-nitrosylation in E. coli is principally dependent on the enzymatic activity of Hcp.
• Showed that NO is produced by nitrate reductase under specific conditions.
• Identified a large S-nitrosylation-dependent interactome regulating cell motility and metabolism.

Conclusions:

• Protein S-nitrosylation by NO in E. coli is predominantly an enzymatic process.
• The identified multiplex enzymatic mechanism may necessitate a re-evaluation of NO-based cellular signaling.
• This study highlights a novel enzymatic pathway for redox signaling.