Sirtuin is a protein with an enzymatic activity of NAD + -dependent protein deacetylation. It was first identified in yeast and its homologous genes have been widely found in various organisms. In bacteria, sirtuin gene was first described as cobB, encoding a cobalamin processing enzyme; and later its potential involvement in regulating acetylation levels of metabolic enzymes, transcription factors, chemotactic proteins and others have been reported. In order to study its physiological relevance in probiotic lactic acid bacteria, we analyzed the whole genome of three L. paracasei strains. All strains tested had sirtuin homolog genes designated hereby as sirA, and one of them had an additional gene designated as sirB. Following confirmation of their coding sequences by individual gene cloning, corresponding recombinant proteins have been generated and purified. The enzymatic characterization revealed that the intrinsic NAD + -dependent deacetylation activity of LpSirA (protein encoded by sirA) is comparable to human SIRT1. Furthermore, by blocking sirtuin activity using nicotinamide in vivo, together with an in vitro deacetylation reaction using recombinant LpSirA, we identified one of the target proteins in the lactic acid bacteria as the 30S ribosomal protein S4 (rpsD product).
The viable cell count of molds,yeasts and lactic acid bacteria was determined on 22 samples of Chinese koji.Mold isolates were examined for their enzyme activity and identified.Results of this study were as follows:1)The microbial count per gram of koji sample was determined.Molds were found to be present on 20 samples with values ranging from 103 to 106.Yeasts were present on 4 samples and the count was 106 to 107,whereas that of lactic acid bacteria which were present on 19 samples gave an average value of 106.2)The enzyme activity of the isolated molds were examined. In general, the activities of enzymes from Chinese kojis were low.3)The mold isolates were identified to be mainly Rhizopus sp.and few strains belonged to Syncephalastrum sp.
This data article provides atomic force microscopy (AFM) amplitude images of botulinum toxin complex (TC) molecules produced by
Clostridium botulinum
serotype D strain.
C. botulinum
produces different-sized TC molecules, such as a complex of botulinum neurotoxin and nontoxic nonhemagglutinin proteins (M-TC) and complex of M-TC and hemagglutinin subcomplex (L-TC). In this data article, the M and L-TC produced by serotype D strain 4947 were imaged by AFM. The M-TC molecule had a globular structure with a 30.5-nm diameter and a 2.1-nm height, while the L-TC molecule had a distinct structure in which several spheres were connected to a globular structure that was 40.7 nm in diameter and 3.5 nm in height.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.