Search results for "030302 biochemistry & molecular biology"

Bio-Sintering/Bio-Fusion of Silica in Sponge Spicules

2012

The synthesis of siliceous spicules in both demosponges and hexactinellids is enzymatically driven via silicatein. This enzyme exists both intra-spicularly and in the extra-spicular space. It catalyzes the formation of bio-silica constituting the silica lamellae that are formed during the appositional (layer-by-layer) growth of the spicules. The extent of (bio-silica forming) activity of silicatein from the demosponge Suberites domuncula measured in vitro reflects the amount of bio-silica required for the formation of spicules in vivo. It is shown that during growth and maturation of the spicules in demosponges a bio-fusion process occurs that results in an intra-spicular sintering of the s…

Characterization of crustacyanin-A2 subunit as a component of the organic matrix of gastroliths from the crayfish Cherax quadricarinatus.

2009

AbstractLike the lobsters, some terrestrial crabs and other crayfishes, the Australian red claw crayfish, Cherax quadricarinatus, elaborates in its stomach wall calcium storage structures called gastroliths. For understanding the cyclic elaboration and stabilization of these amorphous calcified structures, we studied the organic matrix (OM) of these paired biomineralizations. After decalcification with acetic acid, we analysed the proteinaceous components of an acetic acid-insoluble fraction by two-dimensional electrophoresis. Nine spots were digested by trpsin and the tryptic peptides were sequenced by nanoLC-nanoESI-MS/MS mass spectrometry. About 100 peptidic sequences were compared to se…

2019

Mammalian fetuin-A and fetuin-B are abundant serum proteins with pleiotropic functions. Fetuin-B is a highly selective and potent inhibitor of metallopeptidases (MPs) of the astacin family, which includes ovastacin in mammals. By inhibiting ovastacin, fetuin-B is essential for female fertility. The crystal structure of fetuin-B was determined unbound and in complex with archetypal astacin, and it was found that the inhibitor has tandem cystatin-type modules (CY1 and CY2). They are connected by an exposed linker with a rigid, disulfide-linked `CPDCP-trunk', and are followed by a C-terminal region (CTR) with little regular secondary structure. The CPDCP-trunk and a hairpin of CY2 form a bipar…

2021

Parvoviruses are small single-stranded (ss) DNA viruses, which replicate in the nucleoplasm and affect both the structure and function of the nucleus. The nuclear stage of the parvovirus life cycle starts at the nuclear entry of incoming capsids and culminates in the successful passage of progeny capsids out of the nucleus. In this review, we will present past, current, and future microscopy and biochemical techniques and demonstrate their potential in revealing the dynamics and molecular interactions in the intranuclear processes of parvovirus infection. In particular, a number of advanced techniques will be presented for the detection of infection-induced changes, such as DNA modification…

Flipping of alkylated DNA damage bridges base and nucleotide excision repair

2009

Alkyltransferase-like proteins (ATLs) share functional motifs with the cancer chemotherapy target O6-alkylguanine-DNA alkyltransferase (AGT) and paradoxically protect cells from the biological effects of DNA alkylation damage, despite lacking the reactive cysteine and alkyltransferase activity of AGT. Here we determine Schizosaccharomyces pombe ATL structures without and with damaged DNA containing the endogenous lesion O6-methylguanine or cigarette-smoke-derived O6-4-(3-pyridyl)-4-oxobutylguanine. These results reveal non-enzymatic DNA nucleotide flipping plus increased DNA distortion and binding pocket size compared to AGT. Our analysis of lesion-binding site conservation identifies new A…

Flashing light in sponges through their siliceous fiber network: A new strategy of “neuronal transmission” in animals

2012

Sponges (phylum Porifera) represent a successful animal taxon that evolved prior to the Ediacaran-Cambrian boundary (542 million years ago). They have developed an almost complete array of cell- and tissue-based interaction systems necessary for the establishment of a functional, multicellular body. However, a network of neurons, one cell/tissue-communication system is missing in sponges. This fact is puzzling and enigmatic, because these animals possess receptors known to be involved in the nervous system in evolutionary younger animal phyla. As an example, the metabotropic glutamate/GABA-like receptor has been identified and cloned by us. Recently, we have identified a novel light transmi…

The C-terminal domain of ParB is critical for dynamic DNA binding and bridging interactions which condense the bacterial centromere

2017

SUMMARYThe ParB protein forms DNA bridging interactions aroundparSto form networks which condense DNA and earmark the bacterial chromosome for segregation. The mechanism underlying the formation of ParB nucleoprotein complexes is unclear. We show here that the central DNA binding domain is essential for anchoring atparS, and that this interaction is not required for DNA condensation. Structural analysis of the C-terminal domain reveals a dimer with a lysine-rich surface that binds DNA non-specifically and is essential for DNA condensationin vitro. Mutation of either the dimerisation or the DNA binding interface eliminates ParB foci formationin vivo. Moreover, the free C-terminal domain can …

Third International Congress of Histochemistry and Cytochemistry

1968

The tissue distribution of enzymatic activities in intestinal metaplasia stomachs exhibiting chronic gastritis was compared histochemically with that of the small intestine in man.

2'-O-methylation within prokaryotic and eukaryotic tRNA inhibits innate immune activation by endosomal Toll-like receptors but does not affect recogn…

2019

Bacterial RNA has emerged as an important activator of innate immune responses by stimulating Toll-like receptors TLR7 and TLR8 in humans. Guanosine 2′-O-methylation at position 18 (Gm18) in bacterial tRNA was shown to antagonize tRNA-induced TLR7/8 activation, suggesting a potential role of Gm18 as an immune escape mechanism. This modification also occurs in eukaryotic tRNA, yet a physiological immune function remained to be tested. We therefore set out to investigate the immune modulatory role of Gm18 in both prokaryotic and eukaryotic microorganisms, Escherichia coli and Saccharomyces cerevisiae, and in human cells. Using RiboMethSeq analysis we show that mutation of trmH in E. coli, trm…

Crustacean Hemolymph Lipoproteins

2020

Lipoproteins mediate the transport of apolar lipids in the hydrophilic environment of physiological fluids such as the vertebrate blood and the arthropod hemolymph. In this overview, we will focus on the hemolymph lipoproteins in Crustacea that have received most attention during the last years: the high density lipoprotein/β-glucan binding proteins (HDL-BGBPs), the vitellogenins (VGs), the clotting proteins (CPs) and the more recently discovered large discoidal lipoproteins (dLPs). VGs are female specific lipoproteins which supply both proteins and lipids as storage material for the oocyte for later use by the developing embryo. Unusual within the invertebrates, the crustacean yolk protein…