1.Ethylene and 1-MCP regulate major volatile biosynthetic pathways in apple fruit.
Yang X1, Song J2, Du L1, Forney C3, Campbell-Palmer L3, Fillmore S3, Wismer P4, Zhang Z1. Food Chem. 2016 Mar 1;194:325-36. doi: 10.1016/j.foodchem.2015.08.018. Epub 2015 Aug 7.
The effects of ethylene and 1-methylcyclopropene (1-MCP) on apple fruit volatile biosynthesis and gene expression were investigated. Statistical analysis identified 17 genes that changed significantly in response to ethylene and 1-MCP treatments. Genes encoding branched-chain amino acid aminotransferase (BCAT), aromatic amino acid aminotransferase (ArAT) and amino acid decarboxylases (AADC) were up-regulated during ripening and further enhanced by ethylene treatment. Genes related to fatty acid synthesis and metabolism, including acyl-carrier-proteins (ACPs), malonyl-CoA:ACP transacylase (MCAT), acyl-ACP-desaturase (ACPD), lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC2), β-oxidation, acyl-CoA synthetase (ACS), enoyl-CoA hydratase (ECHD), acyl-CoA dehydrogenase (ACAD), and alcohol acyltransferases (AATs) also increased during ripening and in response to ethylene treatment. Allene oxide synthase (AOS), alcohol dehydrogenase 1 (ADH1), 3-ketoacyl-CoA thiolase and branched-chain amino acid aminotransferase 2 (BCAT2) decreased in ethylene-treated fruit.
2.Imido-hydrido complexes of Mo(IV): catalysis and mechanistic aspects of hydroboration reactions.
Khalimon AY1, Farha PM2, Nikonov GI2. Dalton Trans. 2015 Nov 21;44(43):18945-56. doi: 10.1039/c5dt02945g.
Imido-hydrido complexes (ArN)Mo(H)(Cl)(PMe3)3 (1) and (ArN)Mo(H)2(PMe3)3 (2) (Ar = 2,6-diisopropylphenyl) catalyse a variety of hydroboration reactions, including the rare examples of addition of HBCat to nitriles to form bis(borylated) amines RCH2N(BCat)2. Stoichiometric reactivity of complexes 1 and 2 with nitriles and HBCat suggest that catalytic reactions proceed via a series of agostic borylamido and borylamino complexes. For complex 1, catalysis starts with addition of nitriles across the Mo-H bond to give (ArN)Mo(Cl)(N[double bond, length as m-dash]CHR)(PMe3)2; whereas for complex 2 stoichiometric reactions suggest initial addition of HBCat to form the agostic complex Mo(H)2(PMe3)3(η(3)-NAr-HBcat) (16).
3.Functional roles of a predicted branched chain aminotransferase encoded by the LkBAT1 gene of the yeast Lachancea kluyveri.
Montalvo-Arredondo J1, Jiménez-Benítez Á2, Colón-González M3, González-Flores J4, Flores-Villegas M5, González A6, Riego-Ruiz L7. Fungal Genet Biol. 2015 Dec;85:71-82. doi: 10.1016/j.fgb.2015.11.004. Epub 2015 Nov 10.
Branched chain amino acid aminotransferases (BCATs) catalyze the last step of the biosynthesis and the first step of the catabolism of branched chain amino acids. In Saccharomyces cerevisiae, BCATs are encoded by the ScBAT1 and ScBAT2 paralogous genes. Analysis of Lachancea kluyveri genome sequence, allowed the identification of the LkBAT1 locus, which could presumably encode a BCAT. A second unlinked locus (LkBAT1bis), exhibiting sequence similarity to LkBAT1 was also identified. To determine the function of these putative BCATs, L. kluyveri mutant strains lacking LkBAT1, LkBAT1bis or both genes were generated and tested for VIL metabolism. LkBat1 displayed branched chain aminotransferase activity and is required for VIL biosynthesis and catabolism. However, Lkbat1Δ mutant is a valine and isoleucine auxotroph and a leucine bradytroph indicating that L. kluyveri harbors an alternative enzyme(s) involved in leucine biosynthesis. Additionally, heterologous reciprocal gene complementation between S.
