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Exciting Finding (exciting + finding)
Selected AbstractsEvolutionary history of vertebrate appendicular muscleBIOESSAYS, Issue 5 2001Frietson Galis The evolutionary history of muscle development in the paired fins of teleost fish and the limbs of tetrapod vertebrates is still, to a large extent, uncertain. There has been a consensus, however, that in the vertebrate clade the ancestral mechanism of fin and limb muscle development involves the extension of epithelial tissues from the somite into the fin/limb bud. This mechanism has been documented in chondrichthyan, dipnoan, chondrostean and teleost fishes. It has also been assumed that in amniotes, in contrast, individual progenitor cells of muscles migrate from the somites into the limb buds. Neyt et al.(1) now present the exciting finding that in zebrafishes this presumably derived mechanism involving individual cell migration, is present. They conclude, based on data on sharks, zebrafishes, chickens, quails and mice that the derived mechanism was present in the sarcopterygians. This conclusion, however, may be premature in the light of further data available in the literature, which show a highly mosaic distribution of this character in the vertebrate clade. Furthermore, a developmental mode exists that is intermediate between the supposed ancestral and derived modes in teleosts, reptiles and possibly amphibians. BioEssays 23:383,387, 2001. © 2001 John Wiley & Sons, Inc. [source] A double mutation of Escherichia coli 2C -methyl- d -erythritol-2,4-cyclodiphosphate synthase disrupts six hydrogen bonds with, yet fails to prevent binding of, an isoprenoid diphosphateACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2005Tanja Sgraja The essential enzyme 2C -methyl- d -erythritol-2,4-cyclodiphosphate (MECP) synthase, found in most eubacteria and the apicomplexan parasites, participates in isoprenoid-precursor biosynthesis and is a validated target for the development of broad-spectrum antimicrobial drugs. The structure and mechanism of the enzyme have been elucidated and the recent exciting finding that the enzyme actually binds diphosphate-containing isoprenoids at the interface formed by the three subunits that constitute the active protein suggests the possibility of feedback regulation of MECP synthase. To investigate such a possibility, a form of the enzyme was sought that did not bind these ligands but which would retain the quaternary structure necessary to create the active site. Two amino acids, Arg142 and Glu144, in Escherichia coli MECP synthase were identified as contributing to ligand binding. Glu144 interacts directly with Arg142 and positions the basic residue to form two hydrogen bonds with the terminal phosphate group of the isoprenoid diphosphate ligand. This association occurs at the trimer interface and three of these arginines interact with the ligand phosphate group. A dual mutation was designed (Arg142 to methionine and Glu144 to leucine) to disrupt the electrostatic attractions between the enzyme and the phosphate group to investigate whether an enzyme without isoprenoid diphosphate could be obtained. A low-resolution crystal structure of the mutated MECP synthase Met142/Leu144 revealed that geranyl diphosphate was retained despite the removal of six hydrogen bonds normally formed with the enzyme. This indicates that these two hydrophilic residues on the surface of the enzyme are not major determinants of isoprenoid binding at the trimer interface but rather that hydrophobic interactions between the hydrocarbon tail and the core of the enzyme trimer dominate ligand binding. [source] Type III secretion: The bacteria-eukaryotic cell expressFEMS MICROBIOLOGY LETTERS, Issue 1 2005Luís Jaime Mota Abstract Type III secretion (T3S) is an export pathway used by Gram-negative pathogenic bacteria to inject bacterial proteins into the cytosol of eukaryotic host cells. This pathway is characterized by (i) a secretion nanomachine related to the bacterial flagellum, but usually topped by a stiff needle-like structure; (ii) the assembly in the eukaryotic cell membrane of a translocation pore formed by T3S substrates; (iii) a non-cleavable N-terminal secretion signal; (iv) T3S chaperones, assisting the secretion of some substrates; (v) a control mechanism ensuring protein delivery at the right place and time. Here, we review these different aspects focusing in open questions that promise exciting findings in the near future. [source] The cannabinoid CB2 receptor: a good friend in the gutNEUROGASTROENTEROLOGY & MOTILITY, Issue 9 2007A. A. Izzo Abstract, Mammalian tissues express the cannabinoid 1 (CB1) receptor and the cannabinoid 2 (CB2) receptor, the latter being involved in inflammation and pain. In somatic nerve pathways, the analgesic effects of CB2 agonism are well documented. Two papers published in the Journal have provided evidence that CB2 receptor activation inhibits visceral afferent nerve activity in rodents. These exciting findings are discussed in the context of recent data highlighting the emerging role of CB2 receptor as a critical target able to counteract hypermotility in pathophysiological states, gut inflammation and possibly colon cancer. [source] | ||||||||||