Characterisation of the putative Type VII protein secretion system of Streptomyces spp

Streptomyces are Gram-positive bacteria belonging to the Actinobacteria. They are predominantly soil-dwelling saprophytic organisms. S. coelicolor is often used as a model organism for the study of the mechanisms underlying the processes of development and antibiotic production. S. scabies is one of only a few members of the genus that is pathogenic, being the causal agent of common scab of potato. Bioinformatic analysis of the genomes of both S. coelicolor and S. scabies revealed the presence of genes encoding components of putative Type VII protein secretion systems (T7SSs). To investigate the role of these putative T7SSs in S. coelicolor and S. scabies, marked deletions were constructed in genes encoding core components of the machinery. Phenotypic analysis revealed that deletion of genes encoding the T7SS FtsK/SpoIIIE ATPases (FSD) resulted in delayed actinorhodin production in S. coelicolor and slightly accelerated aerial development in S. scabies. In S. scabies, deletion of the genes encoding the WXG100 proteins, canonical substrates of T7SSs, led to a marked reduction in aerial hyphae formation and sporulation, in a media-dependent manner when compared to the wild-type strain. Closer inspection by scanning electron microscopy revealed that the spore chains of these mutant strains were under-developed and spores were irregularly sized. Strains of S. scabies lacking the WXG proteins (but not the FSD protein) were also resistant to lytic infection by the bacteriophage FC31. Taken together, these observations indicate that the major role of the WXG100 proteins in Streptomyces is intracellular.Plant infection assays indicate that the T7SS of S. scabies does not significantly contribute to virulence in several laboratory models of plant infection.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Gene editing enables rapid engineering of complex antibiotic assembly lines

From Springer Nature via Jisc Publications RouterHistory: received 2021-09-09, accepted 2021-11-02, registration 2021-11-08, pub-electronic 2021-11-25, online 2021-11-25, collection 2021-12Publication status: PublishedFunder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); doi: https://doi.org/10.13039/501100000268; Grant(s): BB/L013754/1, BB/N023536/1Abstract: Re-engineering biosynthetic assembly lines, including nonribosomal peptide synthetases (NRPS) and related megasynthase enzymes, is a powerful route to new antibiotics and other bioactive natural products that are too complex for chemical synthesis. However, engineering megasynthases is very challenging using current methods. Here, we describe how CRISPR-Cas9 gene editing can be exploited to rapidly engineer one of the most complex megasynthase assembly lines in nature, the 2.0 MDa NRPS enzymes that deliver the lipopeptide antibiotic enduracidin. Gene editing was used to exchange subdomains within the NRPS, altering substrate selectivity, leading to ten new lipopeptide variants in good yields. In contrast, attempts to engineer the same NRPS using a conventional homologous recombination-mediated gene knockout and complementation approach resulted in only traces of new enduracidin variants. In addition to exchanging subdomains within the enduracidin NRPS, subdomains from a range of NRPS enzymes of diverse bacterial origins were also successfully utilized

The Enigmatic Esx Proteins:Looking Beyond Mycobacteria

Bacteria export proteins across membranes using a range of transport machineries. Type VII secretion systems (T7SSs), originally described in mycobacteria, are now known to be widespread across diverse bacterial phyla. Recent studies have characterized secretion components and mechanisms of type VII secretion in pathogenic and environmental bacteria. A variety of functions have been attributed to T7SS substrates, including interactions with eukaryotes and with other bacteria. Here, we evaluate the growing body of knowledge on T7SSs, with focus on the nonmycobacterial systems, reviewing their phylogenetic distribution, structure and function in diverse settings

Biblical counseling and referral issues

Convocation recorded at Concordia Seminary (Saint Louis, Mo.) on February 3, 1992

New directions for testing and measurement

Publ. comme no 18, june 1983 de la revue New directions for testing and measurementBibliogr. à la fin des textesIndex: p. 103-10

A New Multiple Level Approach to Cross-Cultural Psychological Research

352 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1977.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD