Cryo-EM reveals mechanisms of angiotensin I-converting enzyme allostery and dimerization.

Hypertension (high blood pressure) is a major risk factor for cardiovascular disease, which is the leading cause of death worldwide. The somatic isoform of angiotensin I-converting enzyme (sACE) plays a critical role in blood pressure regulation, and ACE inhibitors are thus widely used to treat hypertension and cardiovascular disease. Our current understanding of sACE structure, dynamics, function, and inhibition has been limited because truncated, minimally glycosylated forms of sACE are typically used for X-ray crystallography and molecular dynamics simulations.

The structures of the C146A variant of the amidase from Pyrococcus horikoshii bound to glutaramide and acetamide suggest the basis of amide recognition.

The nitrilase superfamily enzymes from Pyrococcus abyssi and Pyrococcus horikoshii hydrolyze several different amides. No nitriles that we tested were hydrolyzed by either enzyme. Propionamide and acetamide were the most rapidly hydrolyzed of all the substrates tested.

Detection of a SARS-CoV-2 variant of concern in South Africa.

Continued uncontrolled transmission of SARS-CoV-2 in many parts of the world is creating conditions for substantial evolutionary changes to the virus. Here we describe a newly arisen lineage of SARS-CoV-2 (designated 501Y.V2; also known as B.

Structural Characterization and Directed Evolution of a Novel Acetyl Xylan Esterase Reveals Thermostability Determinants of the Carbohydrate Esterase 7 Family.

A hot desert hypolith metagenomic DNA sequence data set was screened for genes annotated as acetyl xylan esterases (AcXEs). One of the genes identified encoded an ∼36-kDa protein (Axe1). The synthesized gene was cloned and expressed, and the resulting protein was purified.

A new crystal form of MshB from Mycobacterium tuberculosis with glycerol and acetate in the active site suggests the catalytic mechanism.

MshB, a zinc-based deacetylase, catalyses a step in the mycothiol biosynthetic pathway that involves the deacetylation of 1-O-(2-acetamido-2-deoxy-α-D-glucopyranosyl)-D-myo-inositol (GlcNAc-Ins), via cleavage of an amide bond, to 1-O-(2-amino-2-deoxy-α-D-glucopyranosyl)-D-myo-inositol (GlcN-Ins) and acetate. In this study, MshB was expressed, purified and crystallized. A new crystal form was encountered in 0.

Crystal structure of a thermostable old yellow enzyme from Thermus scotoductus SA-01.

Recent characterization of the chromate reductase (CrS) from the thermophile Thermus scotoductus SA-01 revealed this enzyme to be related to the Old Yellow Enzyme (OYE) family. Here, we report the structure of a thermostable OYE homolog in its holoform at 2.2A as well as its complex with p-hydroxybenzaldehyde (pHBA).

The missing link in plant histidine biosynthesis: Arabidopsis myoinositol monophosphatase-like2 encodes a functional histidinol-phosphate phosphatase.

Histidine (His) plays a critical role in plant growth and development, both as one of the standard amino acids in proteins, and as a metal-binding ligand. While genes encoding seven of the eight enzymes in the pathway of His biosynthesis have been characterized from a number of plant species, the identity of the enzyme catalyzing the dephosphorylation of histidinol-phosphate to histidinol has remained elusive. Recently, members of a novel family of histidinol-phosphate phosphatase proteins, displaying significant sequence similarity to known myoinositol monophosphatases (IMPs) have been identified from several Actinobacteria.

Histone octamer helical tubes suggest that an internucleosomal four-helix bundle stabilizes the chromatin fiber.

A major question in chromatin involves the exact organization of nucleosomes within the 30-nm chromatin fiber and its structural determinants of assembly. Here we investigate the structure of histone octamer helical tubes via the method of iterative helical real-space reconstruction. Accurate placement of the x-ray structure of the histone octamer within the reconstructed density yields a pseudoatomic model for the entire helix, and allows precise identification of molecular interactions between neighboring octamers.