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1. Autor: Pátek, Miroslav

10 záznamů v Medvik Filtry

Článek

Stress response in Rhodococcus strains

Pátek, Miroslav
Autor Pátek, Miroslav Institute of Microbiology of the CAS, v. v. i., Prague, Czech Republic. Electronic address: patek@biomed.cas.cz
Grulich, Michal
Autor Grulich, Michal Institute of Microbiology of the CAS, v. v. i., Prague, Czech Republic. Electronic address: grulich@biomed.cas.cz
Nešvera, Jan
Autor Nešvera, Jan Institute of Microbiology of the CAS, v. v. i., Prague, Czech Republic. Electronic address: nesvera@biomed.cas.cz

Biotechnology advances. 2021 ; 53 (-) : 107698. [pub] 20210128

Biotechnol Adv
ISSN 1873-1899
Medvik
Zdroj

Rhodococci are bacteria which can survive under various extreme conditions, in the presence of toxic compounds, and in other hostile habitats. Their tolerance of unfavorable conditions is associated with the structure of their cell wall and their large array of enzymes, which degrade or detoxify harmful compounds. Their physiological and biotechnological properties, together with tools for their genetic manipulation, enable us to apply them in biotransformations, biodegradation and bioremediation. Many such biotechnological applications cause stresses that positively or negatively affect their efficiency. Whereas numerous reviews on rhodococci described their enzyme activities, the optimization of degradation or production processes, and corresponding technological solutions, only a few reviews discussed some specific effects of stresses on the physiology of rhodococci and biotechnological processes. This review aims to comprehensively describe individual stress responses in Rhodococcus strains, the interconnection of different types of stresses and their consequences for cell physiology. We examine here the responses to (1) environmental stresses (desiccation, heat, cold, osmotic and pH stress), (2) the presence of stress-inducing compounds (metals, organic compounds and antibiotics) in the environment (3) starvation and (4) stresses encountered during biotechnological applications. Adaptations of the cell envelope, the formation of multicellular structures and stresses induced by the interactions of hosts with pathogenic rhodococci are also included. The roles of sigma factors of RNA polymerase in the global regulation of stress responses in rhodococci are described as well. Although the review covers a large number of stressful conditions, our intention was to provide an overview of the selected stress responses and their possible connection to biotechnological processes, not an exhaustive survey of the scientific literature. The findings on stress responses summarized in this review and the demonstration of gaps in current knowledge may motivate researchers working to fill these gaps.

Článek

Corynebacterium glutamicum promoters: a practical approach

Microbial biotechnology. 2013 ; 6 (2) : 103-17.

Microb Biotechnol
ISSN 1751-7915
Medvik
Zdroj

Transcription initiation is the key step in gene expression in bacteria, and it is therefore studied for both theoretical and practical reasons. Promoters, the traffic lights of transcription initiation, are used as construction elements in biotechnological efforts to coordinate 'green waves' in the metabolic pathways leading to the desired metabolites. Detailed analyses of Corynebacterium glutamicum promoters have already provided large amounts of data on their structures, regulatory mechanisms and practical capabilities in metabolic engineering. In this minireview the main aspects of promoter studies, the methods developed for their analysis and their practical use in C. glutamicum are discussed. These include definitions of the consensus sequences of the distinct promoter classes, promoter localization and characterization, activity measurements, the functions of transcriptional regulators and examples of practical uses of constitutive, inducible and modified promoters in biotechnology. The implications of the introduction of novel techniques, such as in vitro transcription and RNA sequencing, to C. glutamicum promoter studies are outlined.

Článek

Sigma factors and promoters in Corynebacterium glutamicum

Journal of biotechnology. 2011 ; 154 (2-3) : 101-13. [pub] 20110126

J Biotechnol
ISSN 1873-4863
Medvik
Zdroj

The Corynebacterium glutamicum genome codes for 7 sigma subunits (factors) of RNA polymerase (RNAP): primary sigma factor SigA (σ(A)), primary-like SigB and 5 other alternative sigma factors (SigC, SigD, SigE, SigH and SigM). Each sigma factor is responsible for recognizing promoters of genes belonging to a regulon (sigmulon) involved in specific functions of the cell. Most promoters of C. glutamicum housekeeping genes are recognized by RNAP+σ(A), whereas σ(B) is involved in transcription of a large group of genes active during the transition phase between the exponential and stationary growth phases when various stress factors threaten to damage the cell. The σ(H) regulon consists of the genes involved in heat shock response including those coding for regulators and other sigma factors. It seems therefore that σ(H) occupies a central position in the cross-regulated network of sigma factors and controls their concerted response to various stress conditions in C. glutamicum. The σ(M) factor was found to regulate genes responding to oxidative stress. The main role of σ(E) is to activate genes involved in response to a cell surface stress. Promoters of individual classes recognized by different sigma factors are compiled and the respective consensus sequences of their key recognition motifs (-35 and -10 regions) are derived. In a number of genes, two or more promoters controlled by the same or different sigma factors were discovered. These multiple, overlapping or dual promoters contribute to a complex gene transcription control mechanisms that integrate internal and external signals and tune gene expression in cells as required by environmental and physiological conditions.