Hydrogenases are oxygen-sensitive enzymes that catalyze the conversion between protons and hydrogen. Water-soluble subcomplexes of membrane-bound [NiFe]-hydrogenases (MBH) have been extensively studied for applications in hydrogen-oxygen fuel cells as they are relatively tolerant to oxygen, although even these catalysts are still inactivated in oxidative conditions. Here, the full heterotrimeric MBH of Ralstonia eutropha, including the membrane-integral cytochrome b subunit, was investigated electrochemically using electrodes modified with planar tethered bilayer lipid membranes (tBLM). Cyclic voltammetry and chronoamperometry experiments show that MBH, in equilibrium with the quinone pool in the tBLM, does not anaerobically inactivate under oxidative redox conditions. In aerobic environments, the MBH is reversibly inactivated by O2, but reactivation was found to be fast even under oxidative redox conditions. This enhanced resistance to inactivation is ascribed to the oligomeric state of MBH in the lipid membrane.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4073834 | PMC |
| http://dx.doi.org/10.1021/ja503138p | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The mechanism of mRNA cap recognition.
Nature
January 2025
Department of Chemistry, Columbia University, New York, NY, USA.
During translation initiation, mRNA molecules must be identified and activated for loading into a ribosome. In this rate-limiting step, the heterotrimeric protein eukaryotic initiation factor eIF4F must recognize and productively interact with the 7-methylguanosine cap at the 5' end of the mRNA and subsequently activate the message. Despite its fundamental, regulatory role in gene expression, the molecular events underlying cap recognition and mRNA activation remain unclear.
View Article and Find Full Text PDFRole of Sec61α2 Translocon in Insulin Biosynthesis.
Diabetes
December 2024
Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI.
Translocational regulation of proinsulin biosynthesis in pancreatic β-cells is unknown, although several studies have reported an important accessory role for the Translocon-Associated Protein complex to assist preproinsulin delivery into the endoplasmic reticulum via the heterotrimeric Sec61 translocon (comprising α, β, and γ subunits). The actual protein-conducting channel is the α-subunit encoded either by Sec61A1 or its paralog Sec61A2. Although the underlying channel selectivity for preproinsulin translocation is unknown, almost all studies of Sec61α to date have focused on Sec61α1.
View Article and Find Full Text PDFPhosphorylation patterns in the AT1R C-terminal tail specify distinct downstream signaling pathways.
Sci Signal
August 2024
Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
Different ligands stabilize specific conformations of the angiotensin II type 1 receptor (AT1R) that direct distinct signaling cascades mediated by heterotrimeric G proteins or β-arrestin. These different active conformations are thought to engage distinct intracellular transducers because of differential phosphorylation patterns in the receptor C-terminal tail (the "barcode" hypothesis). Here, we identified the AT1R barcodes for the endogenous agonist AngII, which stimulates both G protein activation and β-arrestin recruitment, and for a synthetic biased agonist that only stimulates β-arrestin recruitment.
View Article and Find Full Text PDFStructural and dynamic changes in P-Rex1 upon activation by PIP and inhibition by IP.
Elife
July 2024
Departments of Biological Sciences and of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, United States.
PIP-dependent Rac exchanger 1 (P-Rex1) is abundantly expressed in neutrophils and plays central roles in chemotaxis and cancer metastasis by serving as a guanine-nucleotide exchange factor (GEF) for Rac. The enzyme is synergistically activated by PIP and heterotrimeric Gβγ subunits, but mechanistic details remain poorly understood. While investigating the regulation of P-Rex1 by PIP, we discovered that Ins(1,3,4,5)P (IP) inhibits P-Rex1 activity and induces large decreases in backbone dynamics in diverse regions of the protein.
View Article and Find Full Text PDFCryo-EM structures of adenosine receptor AAR bound to selective agonists.
Nat Commun
April 2024
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
The adenosine A receptor (AAR), a key member of the G protein-coupled receptor family, is a promising therapeutic target for inflammatory and cancerous conditions. The selective AAR agonists, CF101 and CF102, are clinically significant, yet their recognition mechanisms remained elusive. Here we report the cryogenic electron microscopy structures of the full-length human AAR bound to CF101 and CF102 with heterotrimeric G protein in complex at 3.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!