Chlamydomonas nuclear mutants that fail to assemble respiratory or photosynthetic electron transfer complexes

2001 ◽  
Vol 29 (4) ◽  
pp. 452-455 ◽  
Author(s):  
F. J. Lown ◽  
A. T. Watson ◽  
S. Purton
Keyword(s):  
Electron Transfer ◽  
Green Alga ◽  
Molecular Genetic ◽  
Nuclear Genes ◽  
Genetic Approach ◽  
Structural Components ◽  
Genes Encoding ◽  
Photosynthetic Electron Transfer

We are using a molecular-genetic approach to investigate the role of nuclear genes in the biogenesis of the electron transfer complexes of mitochondria and chloroplasts. Our analysis of nuclear mutants of the green alga Chlamydomonas that are defective in respiration or photosynthesis has led to the identification of genes encoding factors required for the expression of specific organellar genes, and genes encoding structural components of the complexes.

scholarly journals Epigenetic targeting and personalized approaches for AML

Hematology ◽  
2014 ◽  
Vol 2014 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Gail J. Roboz
Keyword(s):  
Molecular Genetic ◽  
Treatment Strategies ◽  
Regulation Of Transcription ◽  
Hematopoietic Stem ◽  
Genetic Characteristics ◽  
Sequencing Technologies ◽  
Recurrent Mutations ◽  
Genes Encoding ◽  
Cell Disorder

Abstract Acute myeloid leukemia (AML) is a genetically heterogeneous clonal hematopoietic stem cell disorder and the majority of patients with AML die from their disease. The treatment paradigms for AML were developed decades ago and, although there have been improvements in the outcomes of selected younger patients and those with specific cytogenetic and molecular genetic characteristics, the overall survival for older patients remains dismal. Over the last few years, next-generation sequencing technologies have identified recurrent mutations in genes encoding proteins involved in the epigenetic regulation of transcription in most patients with AML. This discovery has led to new insights into the role of the epigenome in AML and opens the possibility of epigenetically targeted therapies. This chapter describes how epigenetic dysregulation plays a role in AML and highlights current and future treatment strategies that attempt to exploit epigenetic targets.

scholarly journals PGR5 is required for efficient Q cycle in the cytochrome b6f complex during cyclic electron flow

2019 ◽  
Author(s):  
Felix Buchert ◽  
Laura Mosebach ◽  
Philipp Gäbelein ◽  
Michael Hippler
Keyword(s):  
Electron Transfer ◽  
Reductase Activity ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Redox Activity ◽  
Q Cycle ◽  
Redox Tuning ◽  
Photosynthetic Control ◽  
Photosynthetic Electron Transfer

AbstractProton Gradient Regulation 5 (PGR5) is involved in the control of photosynthetic electron transfer but its mechanistic role is not yet clear. Several models have been proposed to explain phenotypes such as a diminished steady state proton motive force (pmf) and increased photodamage of photosystem I (PSI). Playing a regulatory role in cyclic electron flow (CEF) around PSI, PGR5 contributes indirectly to PSI protection by enhancing photosynthetic control, which is a pH-dependent downregulation of electron transfer at the cytochrome b6f complex (b6f). Here, we re-evaluated the role of PGR5 in the green alga Chlamydomonas reinhardtii and conclude that pgr5 possesses a dysfunctional b6f. Our data indicate that the b6f low-potential chain redox activity likely operated in two distinct modes – via the canonical Q cycle during linear electron flow and via an alternative Q cycle during CEF, attributing a ferredoxin-plastoquinone reductase activity to the b6f. The latter mode allowed efficient oxidation of the low-potential chain in the WT b6f. A switch between the two Q cycle modes was dependent of PGR5 and relied on unknown stromal electron carrier(s), which were a general requirement for b6f activity. In CEF-favouring conditions the electron transfer bottleneck in pgr5 was the b6f and insufficient flexibility in the low-potential chain redox tuning might account for the mutant pmf phenotype and the secondary consequences. Models of our findings are discussed.

A Tale of Two Genomes: Role of a Chloroplast Signal in Coordinating Nuclear and Plastid Genome Expression

1992 ◽  
Vol 19 (4) ◽  
pp. 387 ◽  
Author(s):  
RE Susek ◽  
J Chory
Keyword(s):  
Chloroplast Development ◽  
Photosynthetic Apparatus ◽  
Signal Transduction Pathway ◽  
Nuclear Genes ◽  
Signal Molecules ◽  
Chloroplast Gene Expression ◽  
Genome Expression ◽  
Coordinate Control ◽  
Genes Encoding

Plant cells coordinately regulate the expression of nuclear and plastid genes that encode components of the photosynthetic apparatus. Nuclear genes that regulate chloroplast development and chloroplast gene expression provide part of this coordinate control. However, there is compelling evidence that information also flows in the opposite direction, from chloroplasts to the nucleus. This hypothesised, second pathway functions to coordinate the expression of nuclear genes encoding components of the photosynthetic apparatus with the functional state of the chloroplast. Here we review the evidence for the signal transduction pathway from the chloroplasts to the nucleus and suggest possible signal molecules.

The Molecular Role of the PufX Protein in Bacterial Photosynthetic Electron Transfer

1998 ◽  
pp. 103-116 ◽  
Author(s):  
Francesco Francia ◽  
Paola Turina ◽  
B. Andrea Melandri ◽  
Giovanni Venturoli
Keyword(s):  
Electron Transfer ◽  
Photosynthetic Electron Transfer

scholarly journals Genomic Organization and Molecular Characterization of SM1, a Temperate Bacteriophage of Streptococcus mitis

2003 ◽  
Vol 185 (23) ◽  
pp. 6968-6975 ◽  
Author(s):  
Ian R. Siboo ◽  
Barbara A. Bensing ◽  
Paul M. Sullam
Keyword(s):  
Genomic Organization ◽  
Major Capsid Protein ◽  
Human Platelets ◽  
Structural Proteins ◽  
Structural Components ◽  
Streptococcus Mitis ◽  
Genes Encoding ◽  
Direct Binding

ABSTRACT The direct binding of Streptococcus mitis to human platelets is mediated in part by two proteins (PblA and PblB) encoded by a lysogenic bacteriophage (SM1). Since SM1 is the first prophage of S. mitis that has been identified and because of the possible role of these phage-encoded proteins in virulence, we sought to characterize SM1 in greater detail. Sequencing of the SM1 genome revealed that it consisted of 34,692 bp, with an overall G+C content of 39 mol%. Fifty-six genes encoding proteins of 40 or more amino acids were identified. The genes of SM1 appear to be arranged in a modular, life cycle-specific organization. BLAST analysis also revealed that the proteins of SM1 have homologies to proteins from a wide variety of lambdoid phages. Bioinformatic analyses, in addition to N-terminal sequencing of the proteins, led to the assignment of possible functions to a number of proteins, including the integrase, the terminase, and two major structural proteins. Examination of the phage structural components indicates that the phage head may assemble using stable multimers of the major capsid protein, in a process similar to that of phage r1t. These findings indicate that SM1 may be part of a discrete subfamily of the Siphoviridae that includes at least phages r1t of Lactococcus lactis and SF370.3 of Streptococcus pyogenes.

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