Reprogramming of bacterial virulence by lysine acetylation.

Area of Science:

• Microbiology
• Structural Biology
• Cell Biology

Background:

• Gram-negative bacteria employ diverse virulence factors for host cell invasion.
• CE-clan proteases are known virulence factors with deubiquitinase/deubiquitin-like specific protease activity, some possessing acetyltransferase function.
• The dual activity mechanisms and physiological impacts of these factors remain poorly understood.

Purpose of the Study:

• To elucidate the molecular mechanisms and structural basis of the dual deSUMOylase and autoacetyltransferase activities of the Simkania negevensis virulence factor SnCE1.
• To investigate the regulatory role of lysine acetylation on SnCE1 function and its consequences for host cell manipulation.

Main Methods:

• X-ray crystallography to determine the structures of SnCE1 in apo-state and complexed with SUMO1.
• Biochemical assays to confirm deSUMOylase and autoacetyltransferase activities.
• Cellular localization studies and analysis of mitochondrial morphology in human cells.

Main Results:

• Crystal structures reveal SnCE1 in apo and SUMO1-bound states.
• SnCE1 exhibits efficient deSUMOylase activity and intrinsic autoacetyltransferase activity.
• Acetylation disrupts SnCE1 tetramer formation, hindering SUMO1 binding and modulating autoproteolysis and subcellular localization.

Conclusions:

• Lysine acetylation serves as a regulatory mechanism for SnCE1 virulence, influencing its activity and subcellular distribution within host cells.
• SnCE1 localizes to the endoplasmic reticulum and induces mitochondrial fragmentation in human cells.
• This study provides mechanistic insights into how bacterial virulence factors are reprogrammed by host cell metabolic states through post-translational modifications like acetylation.