RESUMEN
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.
RESUMEN
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).
