Effects of exogenous hemin on the niacin content of aerobically grown Saccharomyces uvarum

In Saccharomyces uvarum aerobically grown in the tryptophan-added medium, the niacin content started to increase when both tryptophan and glucose in the medium had almost been exhausted. In the kynurenine-added medium, the niacin production occurred immediately after incubation started. Hemin added to the medium enhanced total niacin production by increasing the amount of tryptophan metabolized via the kynureninase flux. The results suggest that the niacin biosynthesis from tryptophan was regulated by catabolite repression, which was alleviated by exogenously added hemin.     

N6-methyladenosine (m6A) is an endogenous A3 adenosine receptor ligand

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Protein W, a spore-specific protein in Myxococcus xanthus, formation of a large electron-dense particle in a spore

The gene for the major spore-specific protein, termed protein W, was cloned, and it was found that protein W is composed of 426 amino acid residues including 31% charged (133 residues) and 39% hydrophobic (166 residues) amino acids. In the protein, a motif consisting of five amino acid residues [(V/L/I)–R–E–R–(V/L/I)] is repeated 28 times, and another motif [M–M–(P/G)–Q–G] five times. Protein W is synthesized during a very late stage of development, forming a single, large electron-dense particle (200–400 nm in diameter) inside a spore. X-ray microanalysis of the particle revealed that it contains a high amount of phosphate in addition to calcium and magnesium. It is proposed that protein W consisting of highly charged repetitive sequences is a polyphosphate storage protein to store energy in spores. The disruption of the gene for protein W resulted in delayed fruiting body formation and a lower spore yield.