Sequence and function of the aas gene in Escherichia coli

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• The Escherichia coli aas gene encodes two key enzymatic activities: 2-acyl-GPE acyltransferase and acyl-ACP synthase.
• Understanding the function and regulation of these enzymes is vital for comprehending lipid metabolism and membrane biogenesis.

Purpose of the Study:

• To clone and characterize the E. coli aas gene.
• To elucidate the enzymatic activities and physiological roles of the aas gene product.
• To identify the rate-limiting enzyme in exogenous lysophospholipid incorporation.

Main Methods:

• Gene cloning and DNA sequencing of the aas gene and surrounding regions.
• In vitro enzymatic assays to measure acyltransferase and synthetase activities.
• In vivo studies measuring fatty acid and lysophospholipid incorporation into cell membranes.
• Bioinformatic analysis comparing the predicted amino acid sequence with homologous enzymes.

Main Results:

• The aas gene was cloned, and its sequence determined, revealing an open reading frame encoding an 80.6 kDa protein.
• Overexpression of the aas gene led to increased 2-acyl-GPE acyltransferase and acyl-ACP synthetase activities.
• The aas gene product was confirmed to be involved in the acylation of endogenous 2-acyl-GPE.
• The study identified the aas gene product as the rate-limiting enzyme for exogenous 2-acyllysophospholipid uptake and incorporation.

Conclusions:

• The aas gene product is responsible for both 2-acyl-GPE acyltransferase and acyl-ACP synthetase activities in E. coli.
• The enzyme plays a significant role in membrane lipid synthesis and modification.
• The findings establish the aas gene product as a critical regulator of exogenous lipid incorporation into the bacterial membrane.