Friedreich's ataxia (GAA)n•(TTC)n repeats strongly stimulate mitotic crossovers in Saccharomyces cerevisae

Expansions of trinucleotide GAA•TTC tracts are associated with the human disease Friedreich''s ataxia, and long GAA•TTC tracts elevate genome instability in yeast. We show that tracts of (GAA)₂₃₀•(TTC)₂₃₀ stimulate mitotic crossovers in yeast about 10,000-fold relative to a “normal” DNA sequence; (GAA)_n•(TTC)_n tracts, however, do not significantly elevate meiotic recombination. Most of the mitotic crossovers are associated with a region of non-reciprocal transfer of information (gene conversion). The major class of recombination events stimulated by (GAA)_n•(TTC)_n tracts is a tract-associated double-strand break (DSB) that occurs in unreplicated chromosomes, likely in G1 of the cell cycle. These findings indicate that (GAA)_n•(TTC)_n tracts can be a potent source of loss of heterozygosity in yeast.     

Molecular docking analysis of bioactive compounds from Cissampelos pareira with PPAR gamma

We document the Molecular docking analysis of bioactive compounds from Cissampelos pareira with PPAR gamma for further consideration in drug discovery for T2DM.     

An efficient process for production and purification of hyaluronic acid from <Emphasis Type="Italic">Streptococcus </Emphasis><Emphasis Type="Italic">equi</Emphasis> subsp. <Emphasis Type="Italic">zooepidemicus</Emphasis>

Growth of Streptococcus zooepidemicus in a 10 l bioreactor with 50 g sucrose/l and 10 g casein hydrolysate/l gave 5–6 g hyaluronic acid/l after 24–28 h. Purification of hyaluronic acid gave a recovery of 65% with the final material having an Mr of ∼4 × 10⁶ Da with less than 0.1% protein.     

Biosynthesis of coronatine,a thermoregulated phytotoxin produced by the phytopathogen Pseudomonas syringae

Coronatine (COR) is a non-host-specific phytotoxin that is produced by several different pathovars in the species Pseudomonas syringae. COR consists of two distinct components: coronafacic acid (CFA), which is synthesized via the polyketide pathway, and coronamic acid (CMA), a cyclized derivative of isoleucine. Both CFA and CMA function as intermediates in the pathway to COR and must be joined together by an amide bond to form the phytotoxin. Although the mode of action for COR remains obscure, the CFA moiety is a structural and functional analogue of jasmonic acid, a compound that is produced in a variety of plants in response to stress. The COR biosynthetic gene cluster generally occurs on large plasmids in P. syringae, an observation that helps to explain the production of COR by multiple pathovars. Mutagenesis, feeding studies, and complementation analyses have been used to divide the COR biosynthetic gene cluster into functional regions. Nucleotide sequencing of the regions involved in CFA and CMA biosynthesis has revealed relatedness to genes encoding polyketide and peptide synthetases, respectively. The deduced amino acid sequence of the gene responsible for catalyzing amide bond formation between CMA and CFA shows relatedness to enzymes that activate cyclic carboxylic acids by adenylation. Coronatine biosynthesis has been shown to be temperature-sensitive and regulated by a modified two-component regulatory system. Received: 12 February 1996 / Accepted: 8 May 1996