Regulation of Bacterial Antibiotic Production

Chater, Keith F.; Bibb, Mervyn J.

doi:10.1002/9783527620890.ch2

Cited by 80 publications

(24 citation statements)

References 182 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Secondary metabolism in actinomycetes is regulated through a complex cascade of regulatory factors [1,3]. In the model organism, Streptomyces coelicolor, several pleiotropic and pathway-specific transcriptional activators, such as actII-ORF4 and redD, have been identified and are relatively well studied [1].…”

Section: Introductionmentioning

confidence: 99%

Constitutive overexpression of asm2 and asm39 increases AP-3 production in the actinomycete Actinosynnema pretiosum

Chin

Wong

2009

J Ind Microbiol Biotechnol

View full text Add to dashboard Cite

Constitutive overexpression of regulators in the ansamitocin biosynthetic cluster of Actinosynnema pretiosum was investigated as a strategy to increase the production of ansamitocin-P3 (AP-3), a clinically promising chemotherapeutic agent. Putative transcriptional regulators asm2, asm29, and asm34 as well as the putative regulatory protein asm39 were cloned into a single-site integrative vector and a multicopy replicative vector, pAP40 and pREP, respectively, and then transformed into A. pretiosum. Transformants overexpressing asm2 and asm39 in pREP showed an increase in ansamitocin production (1.3-fold over parental levels) in a bioassay screen. In shake-flask fermentations, the asm2 and asm39 overexpression transformants attained a maximum AP-3 titer of 33 and 52 mg/l, respectively, which were 1.6- and 2.5-fold higher than the blank vector control. The increase in AP-3 production for the asm2 overexpression transformant was unexpected, since prior reports suggested that Asm2 was a transcriptional repressor. The increase in production appeared to be dependent on the high expression levels achieved with the replicative vector, which may have disrupted the normal function of Asm2. Quantitative reverse-transcription polymerase chain reaction (RT-PCR) confirmed that asm2 and asm39 transcription levels were significantly higher in the transformants relative to the control, suggesting that the yield improvement was due to the transformed plasmids. This study demonstrates that deregulated overexpression of regulatory genes is a feasible strategy to increase AP-3 production in A. pretiosum.

show abstract

Section: Introductionmentioning

confidence: 99%

Constitutive overexpression of asm2 and asm39 increases AP-3 production in the actinomycete Actinosynnema pretiosum

Chin

Wong

2009

J Ind Microbiol Biotechnol

View full text Add to dashboard Cite

show abstract

“…Environmental stimuli such as nutrient limitation, growth rate and cell density, as monitored with signaling compounds, are factors controlling the hierarchical regulation of secondary metabolite biosynthesis [8]. Although the regulatory mechanisms controlling the biosynthetic pathway for CA are not fully understood, the Wndings in the current report indicate that the genes downstream of the CA-CM gene clusters may play a part in the hierarchical RT-PCR analyses of the transcripts from ccaR and claR, genes encoding regulators of CA and CM biosynthesis.…”

Section: Discussionmentioning

confidence: 99%

A gene located downstream of the clavulanic acid gene cluster in Streptomyces clavuligerus ATCC 27064 encodes a putative response regulator that affects clavulanic acid production

Song

Kim

et al. 2008

J Ind Microbiol Biotechnol

View full text Add to dashboard Cite

Three open reading frames denoted as orf21, orf22, and orf23 were identified from downstream of the currently recognized gene cluster for clavulanic acid biosynthesis in Streptomyces clavuligerus ATCC 27064. The new orfs were annotated after in silico analysis as genes encoding a putative sigma factor, a sensor kinase, and a response regulator. The roles of the individual genes were explored by disruption of the corresponding orfs, and the morphological and antibiotic production phenotypes of the resulting mutants were compared. In orf21 and orf22 mutants, no growth or morphological differences were noted, but modest reduction of cephamycin C (orf21), or both cephamycin C and clavulanic acid production (orf22) compared with wild-type, were observed. In orf23 mutant, cell growth and sporulation was retarded, and clavulanic acid and cephamycin C production were reduced to 40 and 47% of wild-type levels, respectively. Conversely, overexpression of orf23 caused precocious hyperproduction of spores on solid medium, and antibiotic production was increased above the levels seen in plasmid control cultures. Transcriptional analyses were also carried out on orf23 and showed that mutation had little effect on transcription of genes associated with the early stages of cephamycin C or clavulanic acid production but transcription of claR, which regulates the late stages of clavulanic acid production, was reduced in orf23 mutants. These observations suggest that the orf23 product may enable S. clavuligerus to respond to environmental changes by altering cell growth and differentiation. In addition, the effects of ORF23 on growth might indirectly regulate the biosynthesis of secondary metabolites such as clavulanic acid and cephamycin C.

show abstract

“…Soon, transformation, conjugation and recombinant DNA technologies became routine tools of the trade [16], being employed to achieve the following goals: (1) removing bottlenecks of ratelimiting reactions, (2) eliminating feedback regulation, (3) manipulating control genes, (4) perturbing central metabolism, (5) blocking competing pathways, (6) enhancing product excretion [26], and (7) decreasing the conversion of the desired product to a less active or inactive compound. An example of each strategy is as follows: (1) the expandase promoter of the penicillin biosynthetic pathway was replaced by the stronger ethanol dehydrogenase promoter [33]; (2) the threonine dehydratase gene ilvA of Corynebacterium glutamicum was replaced with a feedback-resistant ilvA from E. coli to increase isoleucine production [25]; (3) extra copies of positive control genes were inserted in actinomycete producers of actinorhodin, undecylprodigiosin and spiramycin whereas negative regulatory genes were deleted or inactivated in producers of methylenomycin, tetracenomycin, jadomycin, and daunorubicin [10]; (4) the first or second enzyme of the pentose phosphate pathway was deleted in Streptomyces lividans to increase actinorhodin production [9]; (5) tyrosine formation was blocked to increase phenylalanine titer [4]; (6) lysE, encoding the protein involved in lysine excretion, was overexpressed which increased lysine formation in C. glutamicum [52]; and (7) genes dnrX, dnrH and/or dnrU, involved in conversion of the desirable doxorubicin to other compounds, were disrupted, thus increasing doxorubicin titer by threefold [35]. Increasing the dosage of biosynthetic genes has become a popular means to increase production.…”

Section: Laboratory Fermentation Improvementmentioning

confidence: 99%

From natural products discovery to commercialization: a success story

Demain

2006

J IND MICROBIOL BIOTECHNOL

117

View full text Add to dashboard Cite

In order for a natural product to become a commercial reality, laboratory improvement of its production process is a necessity since titers produced by wild strains could never compete with the power of synthetic chemistry. Strain improvement by mutagenesis has been a major success. It has mainly been carried out by "brute force" screening or selection, but modern genetic technologies have entered the scene in recent years. For every new strain developed genetically, there is further opportunity to raise titers by medium modifications. Of major interest has been the nutritional control by induction, as well as inhibition and repression by sources of carbon, nitrogen, phosphate and end products. Both strain improvement and nutritional modification contribute to the new process, which is then scaled up by biochemical engineers into pilot scale and later into factory size fermentors.

show abstract

Regulation of Bacterial Antibiotic Production

Cited by 80 publications

References 182 publications

Constitutive overexpression of asm2 and asm39 increases AP-3 production in the actinomycete Actinosynnema pretiosum

Constitutive overexpression of asm2 and asm39 increases AP-3 production in the actinomycete Actinosynnema pretiosum

A gene located downstream of the clavulanic acid gene cluster in Streptomyces clavuligerus ATCC 27064 encodes a putative response regulator that affects clavulanic acid production

From natural products discovery to commercialization: a success story

Contact Info

Product

Resources

About