Biology subjects

Da Silva, E. B.

Publications and source records attributed to Da Silva, E. B..

3 recordsLinked to original sources

bioRxiv2024

Structure elucidation, biosynthetic gene cluster distribution, and biological activities of ketomemicin analogs in Salinispora

We report three new ketomemicin pseudopeptides (1-3) from extracts of the marine actinomycete Salinispora pacifica strain CNY-498. Their constitution and relative configuration were elucidated using NMR, mass spectrometry, and quantum chemical calculations. Using GNPS molecular networking and publicly available Salinispora LCMS datasets, five additional ketomemicin analogs (4-8) were identified with ketomemicin production detected broadly across Salinispora species. The ketomemicin biosynthetic gene cluster (ktm) is highly conserved in Salinispora, occurring in 79 of 118 public genome sequences including eight of the nine named species. Outside Salinispora, ktm homologs were detected in various genera of the phylum Actinomycetota that might encode novel ketomemicin analogs. Ketomemicins 1-3 were tested against a panel of eleven proteases, with 2 displaying moderate inhibitory activity. This study describes the first report of ketomemicin production by Salinispora cultures, the distribution of the corresponding biosynthetic gene cluster, and the protease inhibitory activity of new ketomemicin derivatives. Table of Content/Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=64 SRC="FIGDIR/small/620863v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@481b56org.highwire.dtl.DTLVardef@1fad340org.highwire.dtl.DTLVardef@433ffaorg.highwire.dtl.DTLVardef@11d5d33_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Development of subunit selective proteasome substrates for Schistosoma species

Schistosomiasis, or bilharzia, is a neglected tropical disease caused by Schistosoma spp. blood flukes that infects over 200 million people worldwide. Just one partially effective drug is available, and new drugs and drug targets would be welcome. The 20S proteasome is a validated drug target for many parasitic infections, including those caused by Plasmodium and Leishmania. We previously showed that anticancer proteasome inhibitors that act through the Schistosoma mansoni 20S proteasome (Sm20S) kill the parasite in vitro. To advance these initial findings, we employed Multiplex Substrate Profiling by Mass Spectrometry (MSP-MS) to define the substrate cleavage specificities of the three catalytic {beta} subunits of purified Sm20S. The profiles in turn were used to design and synthesize subunit-specific optimized substrates that performed two to eight fold better than the equivalent substrates used to measure the activity of the constitutive human proteasome (c20S). These specific substrates also eliminated the need to purify Sm20S from parasite extracts - a single step enrichment was sufficient to accurately measure substrate hydrolysis and its inhibition with proteasome inhibitors. Finally, we show that the substrate and inhibition profiles for the 20S proteasome from the three medically important schistosome species are similar, suggesting that data arising from an inhibitor development campaign that focuses on Sm20S can be extrapolated to the other two targets with consequent time and cost savings.

biochemistry↗

bioRxiv2021

Intramolecular interactions enhance the potency of gallinamide A analogs against Trypanosoma cruzi

Gallinamide A, a metabolite of the marine cyanobacterium Schizothrix sp., selectively inhibits cathepsin L-like cysteine proteases. We evaluated potency of gallinamide A and 23 synthetic analogs against intracellular Trypanosoma cruzi amastigotes and the cysteine protease, cruzain. We determined the co-crystal structures of cruzain with gallinamide A and two synthetic analogs at [~]2[A]. SAR data revealed that the N-terminal end of gallinamide A is loosely bound and weakly contributes in drug-target interactions. At the C-terminus, the intramolecular {pi}-{pi} stacking interactions between the aromatic substituents at P1 and P1 restrict the bioactive conformation of the inhibitors, thus minimizing the entropic loss associated with target binding. Molecular dynamics simulations showed that in the absence of an aromatic group at P1, the substituent at P1 interacts with tryptophan-184. The P1-P1 interactions had no effect on anti-cruzain activity whereas anti-T. cruzi potency increased by [~]5-fold, likely due to an increase in solubility/permeability of the analogs.

molecular biology↗