Myocardial protein kinases: I. Properties of soluble and membrane-bound catalytic subunits

Chlamydia is an obligate intracellular bacterium and the most common reportable cause of human infection in the U.S. This pathogen proliferates inside a eukaryotic host cell, where it resides within a membrane-bound compartment called the chlamydial inclusion. It has an unusual developmental cycle, marked by conversion between a replicating form, the reticulate body (RB), and an infectious form, the elementary body (EB). We found that the small molecule H89 slowed inclusion growth and decreased overall RB replication by 2-fold, but caused a 25-fold reduction in infectious EBs. This disproportionate effect on EB production was mainly due to a defect in RB-to-EB conversion and not to the induction of chlamydial persistence, which is an altered growth state. Although H89 is a known inhibitor of specific protein kinases and vesicular transport to and from the Golgi, it did not cause these anti-chlamydial effects by blocking the protein kinases PKA or PKC, or by inhibiting protein or lipid transport. H89 is thus a novel anti-chlamydial compound that has a unique combination of effects on the intracellular Chlamydia infection.

Download Full-text

Involvement of hydrogenases in the formation of highly catalytic Pd(0) nanoparticles by bioreduction of Pd(II) using Escherichia coli mutant strains

Microbiology ◽

10.1099/mic.0.036681-0 ◽

2010 ◽

Vol 156 (9) ◽

pp. 2630-2640 ◽

Cited By ~ 118

Author(s):

Kevin Deplanche ◽

Isabelle Caldelari ◽

Iryna P. Mikheenko ◽

Frank Sargent ◽

Lynne E. Macaskie

Keyword(s):

Escherichia Coli ◽

Mutant Strain ◽

Membrane Separation ◽

Reductase Activity ◽

Reduction Process ◽

Hydrogenase Activity ◽

Catalytic Subunits ◽

E Coli ◽

Economic Production ◽

Membrane Bound

Escherichia coli produces at least three [NiFe] hydrogenases (Hyd-1, Hyd-2 and Hyd-3). Hyd-1 and Hyd-2 are membrane-bound respiratory isoenzymes with their catalytic subunits exposed to the periplasmic side of the membrane. Hyd-3 is part of the cytoplasmically oriented formate hydrogenlyase complex. In this work the involvement of each of these hydrogenases in Pd(II) reduction under acidic (pH 2.4) conditions was studied. While all three hydrogenases could contribute to Pd(II) reduction, the presence of either periplasmic hydrogenase (Hyd-1 or Hyd-2) was required to observe Pd(II) reduction rates comparable to the parent strain. An E. coli mutant strain genetically deprived of all hydrogenase activity showed negligible Pd(II) reduction. Electron microscopy suggested that the location of the resulting Pd(0) deposits was as expected from the subcellular localization of the particular hydrogenase involved in the reduction process. Membrane separation experiments established that Pd(II) reductase activity is membrane-bound and that hydrogenases are required to initiate Pd(II) reduction. The catalytic activity of the resulting Pd(0) nanoparticles in the reduction of Cr(VI) to Cr(III) varied according to the E. coli mutant strain used for the initial bioreduction of Pd(II). Optimum Cr(VI) reduction, comparable to that observed with a commercial Pd catalyst, was observed when the bio-Pd(0) catalytic particles were prepared from a strain containing an active Hyd-1. The results are discussed in the context of economic production of novel nanometallic catalysts.

Download Full-text

Alternative Splicing in Oncogenic Kinases: From Physiological Functions to Cancer

Journal of Nucleic Acids ◽

10.1155/2012/639062 ◽

2012 ◽

Vol 2012 ◽

pp. 1-14 ◽

Cited By ~ 16

Author(s):

Sabine Druillennec ◽

Coralie Dorard ◽

Alain Eychène

Keyword(s):

Alternative Splicing ◽

Protein Kinases ◽

Tyrosine Kinases ◽

Genetic Model ◽

Physiological Functions ◽

Model Studies ◽

Eukaryotic Genes ◽

Membrane Bound ◽

Oncogenic Protein ◽

Encoding Protein

Among the 518 protein kinases encoded by the human kinome, several of them act as oncoproteins in human cancers. Like other eukaryotic genes, oncogenes encoding protein kinases are frequently subjected to alternative splicing in coding as well as noncoding sequences. In the present paper, we will illustrate how alternative splicing can significantly impact on the physiological functions of oncogenic protein kinases, as demonstrated by mouse genetic model studies. This includes examples of membrane-bound tyrosine kinases receptors (FGFR2, Ret, TrkB, ErbB4, and VEGFR) as well as cytosolic protein kinases (B-Raf). We will further discuss how regular alternative splicing events of these kinases are in some instances implicated in oncogenic processes during tumor progression (FGFR, TrkB, ErbB2, Abl, and AuroraA). Finally, we will present typical examples of aberrant splicing responsible for the deregulation of oncogenic kinases activity in cancers (AuroraB, Jak2, Kit, Met, and Ron).

Download Full-text