A shape-shifting nuclease unravels structured RNA.

RNA turnover pathways ensure appropriate gene expression levels by eliminating unwanted transcripts. Dis3-like 2 (Dis3L2) is a 3'-5' exoribonuclease that plays a critical role in human development. Dis3L2 independently degrades structured substrates, including coding and noncoding 3' uridylated RNAs.

Active and Passive Destabilization of G-Quadruplex DNA by the Telomere POT1-TPP1 Complex.

Chromosome ends are protected by guanosine-rich telomere DNA that forms stable G-quadruplex (G4) structures. The heterodimeric POT1-TPP1 complex interacts specifically with telomere DNA to shield it from illicit DNA damage repair and to resolve secondary structure that impedes telomere extension. The mechanism by which POT1-TPP1 accomplishes these tasks is poorly understood.

Alternative RNA degradation pathways by the exonuclease Pop2p from .

The 3' to 5' exonuclease Pop2p (Caf1p) is part of the CCR4-NOT deadenylation complex that removes poly(A) tails from mRNAs in cells. Pop2p is structurally conserved in eukaryotes, but Pop2p harbors noncanonical amino acids in its catalytic center. The enzymatic properties of Pop2p are not well defined.

Binding of a viral IRES to the 40S subunit occurs in two successive steps mediated by eS25.

The mechanism for how internal ribosome entry sites (IRESs) recruit ribosomes to initiate translation of an mRNA is not completely understood. We investigated how a 40S subunit was recruited by the cricket paralysis virus intergenic region (CrPV IGR) IRES to form a stable 40S-IRES complex. Kinetic binding studies revealed that formation of the complex between the CrPV IGR and the 40S subunit consisted of two-steps: an initial fast binding step of the IRES to the 40S ribosomal subunit, followed by a slow unimolecular reaction consistent with a conformational change that stabilized the complex.

Substrate selectivity by the exonuclease Rrp6p.

The exoribonuclease Rrp6p is critical for RNA decay in the nucleus. While Rrp6p acts on a large range of diverse substrates, it does not indiscriminately degrade all RNAs. How Rrp6p accomplishes this task is not understood.

Transcellular transport of cobalamin in aortic endothelial cells.

Cobalamin [Cbl (or B)] deficiency causes megaloblastic anemia and a variety of neuropathies. However, homeostatic mechanisms of cyanocobalamin (CNCbl) and other Cbls by vascular endothelial cells are poorly understood. Herein, we describe our investigation into whether cultured bovine aortic endothelial cells (BAECs) perform transcytosis of B, namely, the complex formed between serum transcobalamin and B, designated as holo-transcobalamin (holo-TC).

Ethanol-induced oxidative stress via the CYP2E1 pathway disrupts adiponectin secretion from adipocytes.

Background: Adipose tissue is an important target for ethanol action. One important effect of ethanol is to reduce the secretion of adiponectin from adipocytes; this decrease is associated with lowered circulating adiponectin in rodent models of chronic ethanol feeding. Adiponectin is an insulin-sensitizing, anti-inflammatory adipokine; decreased adiponectin activity may contribute to tissue injury in response to chronic ethanol.

High resolution crystal structure of the methylcobalamin analogues ethylcobalamin and butylcobalamin by X-ray synchrotron diffraction.

The X-ray crystal structures of the methylcobalamin (MeCbl) analogues ethylcobalamin (EtCbl) and butylcobalamin (BuCbl) are reported. The X-ray crystal structures of EtCbl and BuCbl were obtained with some of the lowest crystallographic residuals ever achieved for cobalamins (R = 0.0468 and 0.

Taurine supplementation prevents ethanol-induced decrease in serum adiponectin and reduces hepatic steatosis in rats.

Unlabelled: Chronic ethanol feeding decreases expression of adiponectin by adipocytes and circulating adiponectin. Adiponectin treatment during chronic ethanol feeding prevents liver injury in mice. Chronic ethanol feeding also increases oxidative and endoplasmic reticulum (ER) stress in adipose tissue.

Accurate assessment and identification of naturally occurring cellular cobalamins.

Background: Accurate assessment of cobalamin profiles in human serum, cells, and tissues may have clinical diagnostic value. However, non-alkyl forms of cobalamin undergo beta-axial ligand exchange reactions during extraction, which leads to inaccurate profiles having little or no diagnostic value.

Methods: Experiments were designed to: 1) assess beta-axial ligand exchange chemistry during the extraction and isolation of cobalamins from cultured bovine aortic endothelial cells, human foreskin fibroblasts, and human hepatoma HepG2 cells, and 2) to establish extraction conditions that would provide a more accurate assessment of endogenous forms containing both exchangeable and non-exchangeable beta-axial ligands.

Genes of the thymidine salvage pathway: thymine-7-hydroxylase from a Rhodotorula glutinis cDNA library and iso-orotate decarboxylase from Neurospora crassa.

Genes for two enzymes in the thymidine salvage pathway, thymine-7-hydroxylase (THase; official name thymine dioxygenase) and iso-orotate decarboxylase (IDCase) have been isolated from fungal sources. THase was isolated from a Rhodotorula glutinis cDNA library using a degenerate oligonucleotide based on the published amino acid sequence. The coding sequence was transferred to an Escherichia coli expression system, from which recombinant THase activity was measured using 14C-labeled thymine.