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Attractive Model System (attractive + model_system)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Critical contact residues that mediate polymerization of nematode major sperm protein

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008
Antonio del Castillo-Olivares
Abstract The polymerization of protein filaments provides the motive force in a variety of cellular processes involving cell motility and intracellular transport. Regulated assembly and disassembly of the major sperm protein (MSP) underlies amoeboid movement in nematode sperm, and offers an attractive model system for characterizing the biomechanical properties of filament formation and force generation. To that end, structure-function studies of MSP from the nematode Caenorhabditis elegans have been performed. Recombinant MSP was purified from Escherichia coli using a novel affinity chromatography technique, and filament assembly was assessed by in vitro polymerization in the presence of polyethylene glycol. Prior molecular studies and structure from X-ray crystallography have implicated specific residues in protein,protein interactions necessary for filament assembly. Purified MSP containing substitutions in these residues fails to form filaments in vitro. Short peptides based on predicted sites of interaction also effectively disrupt MSP polymerization. These results confirm the structural determination of intermolecular contacts and demonstrate the importance of these residues in MSP assembly. J. Cell. Biochem. 104: 477,487, 2008. © 2007 Wiley-Liss, Inc. [source]

Design of a minimal protein oligomerization domain by a structural approach

PROTEIN SCIENCE, Issue 12 2000
Peter Burkhard
Abstract Because of the simplicity and regularity of the ,-helical coiled coil relative to other structural motifs, it can be conveniently used to clarify the molecular interactions responsible for protein folding and stability. Here we describe the de novo design and characterization of a two heptad-repeat peptide stabilized by a complex network of inter- and intrahelical salt bridges. Circular dichroism spectroscopy and analytical ultracentrifugation show that this peptide is highly ,-helical and 100% dimeric under physiological buffer conditions. Interestingly, the peptide was shown to switch its oligomerization state from a dimer to a trimer upon increasing ionic strength. The correctness of the rational design principles used here is supported by details of the atomic structure of the peptide deduced from X-ray crystallography. The structure of the peptide shows that it is not a molten globule but assumes a unique, native-like conformation. This de novo peptide thus represents an attractive model system for the design of a molecular recognition system. [source]

Distribution of sex steroid hormone receptors in the brain of an African cichlid fish, Astatotilapia burtoni

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 16 2010
Lauren A. Munchrath
Abstract Sex steroid hormones released from the gonads play an important role in mediating social behavior across all vertebrates. Many effects of these gonadal hormones are mediated by nuclear steroid hormone receptors, which are crucial for integration in the brain of external (e.g., social) signals with internal physiological cues to produce an appropriate behavioral output. The African cichlid fish Astatotilapia burtoni presents an attractive model system for the study of how internal cues and external social signals are integrated in the brain as males display robust plasticity in the form of two distinct, yet reversible, behavioral and physiological phenotypes depending on the social environment. In order to better understand where sex steroid hormones act to regulate social behavior in this species, we have determined the distribution of the androgen receptor, estrogen receptor alpha, estrogen receptor beta, and progesterone receptor mRNA and protein throughout the telencephalon and diencephalon and some mesencephalic structures of A. burtoni. All steroid hormone receptors were found in key brain regions known to modulate social behavior in other vertebrates including the proposed teleost homologs of the mammalian amygdalar complex, hippocampus, striatum, preoptic area, anterior hypothalamus, ventromedial hypothalamus, and ventral tegmental area. Overall, there is high concordance of mRNA and protein labeling. Our results significantly extend our understanding of sex steroid pathways in the cichlid brain and support the important role of nuclear sex steroid hormone receptors in modulating social behaviors in teleosts and across vertebrates. J. Comp. Neurol. 518:3302,3326, 2010. © 2010 Wiley-Liss, Inc. [source]

Immunity to vacuolar pathogens: What can we learn from Legionella?

CELLULAR MICROBIOLOGY, Issue 11 2004
Annie L. Neild
Summary Intracellular pathogens can manipulate host cellular pathways to create specialized organelles. These pathogen-modified vacuoles permit the survival and replication of bacterial and protozoan microorganisms inside of the host cell. By establishing an atypical organelle, intracellular pathogens present unique challenges to the host immune system. To understand pathogenesis, it is important to not only investigate how these organisms create unique subcellular compartments, but to also determine how mammalian immune systems have evolved to detect and respond to pathogens sequestered in specialized vacuoles. Recent studies have identified genes in the respiratory pathogen Legionella pneumophila that are essential for establishing a unique endoplasmic reticulum-derived organelle inside of mammalian macrophages, making this pathogen an attractive model system for investigations on host immune responses that are specific for bacteria that establish vacuoles disconnected from the endocytic pathway. This review will focus on the host immune response to Legionella and highlight areas of Legionella research that should help elucidate host strategies to combat infections by intracellular pathogens. [source]