Engineering of methionine-auxotroph via parallel evolution of two enzymes from direct-sulfurylation pathway enables its recovery in minimal medium.

Methionine biosynthesis relies on the sequential catalysis of multiple enzymes. , the main bacteria used in research and industry for protein production and engineering, utilizes the three-step trans-sulfurylation pathway catalyzed by L-homoserine O-succinyl transferase, cystathionine gamma synthase and cystathionine beta lyase to convert L-homoserine to L-homocysteine. However, most bacteria employ the two-step direct-sulfurylation pathway involving L-homoserine O-acetyltransferases and O-acetyl homoserine sulfhydrylase.

Conversion of methionine biosynthesis in Escherichia coli from trans- to direct-sulfurylation enhances extracellular methionine levels.

Methionine is an essential amino acid in mammals and a precursor for vital metabolites required for the survival of all organisms. Consequently, its inclusion is required in diverse applications, such as food, feed, and pharmaceuticals. Although amino acids and other metabolites are commonly produced through microbial fermentation, high-yield biosynthesis of L-methionine remains a significant challenge due to the strict cellular regulation of the biosynthesis pathway.

Plasma Cell Gingivitis: Clinical and Pathological Case Report.

Introduction: Plasma cell gingivitis (PCG) is a rare benign condition usually found on marginal and attached gingiva. This case details a generalized PCG, to include the management of the patient and clinicopathologic characteristics of the disorder.

Case Presentation: The patient, a 24-year-old African American female, was referred to the periodontics clinic for severe generalized gingival erythema and edema.

Piezoelectrically Tuned Multimode Cavity Search for Axion Dark Matter.

The μeV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches.