Mcchs1 , a Member of a Chitin Synthase Gene Family in Mucor circinelloides , Is Differentially Expressed During Dimorphism

Ma, Lŏpez-Matas; Ap, Eslava; Jm, Díaz-Mínguez

doi:10.1007/s002849910034

Cited by 14 publications

(8 citation statements)

References 32 publications

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“…This suggests that it is possible that the presence of four pkaR genes is due to multiple rounds of whole-genome duplications, duplication of segments smaller than the entire genome, or duplications in individual genes. Although wholegenome duplication in the Zygomycetes phylogenetic branch is not supported yet by whole-genome analyses, gene duplication is a recurrent theme in Zygomycetes biology, and many examples have been published (16,18,39). Moreover, a comparative study of 34 complete fungal genome sequences, representing a broad diversity of Ascomycetes and Basidiomycetes species, and the zygomycete R. oryzae, showed that the multiplicity of isoforms for one protein varies greatly between fungal species, but the zygomycete R. oryzae possesses by far the highest number of duplication clusters of all of the fungi analyzed (9).…”

Section: Discussionmentioning

confidence: 99%

A Subunit of Protein Kinase A Regulates Growth and Differentiation in the FungusMucor circinelloides

et al. 2009

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The cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling pathway plays a role in regulating development, growth, and virulence in a number of fungi. To determine whether PKA plays a similar function in zygomycete fungi, a mutant of Mucor circinelloides was generated that lacks pkaR1, one of the regulatory subunits of PKA. The mutant showed a reduction in growth and alterations in germination rates, cell volume, germ tube length, and asexual sporulation. The lack of pkaR1 gene resulted in a highly decreased, but not null, cAMP binding activity and in a protein kinase activity that was still dependent on cAMP, although with a higher ؊/؉ cAMP activity ratio, suggesting the existence of other cAMP binding activities. Consequently, three proteins analogous to pkaR1 were predicted from the recently sequenced genome of M. circinelloides and were named pkaR2, pkaR3, and pkaR4. Two of the proteins, pkaR2 and pkaR3, with cAMP binding activity were isolated from the wild-type strain and identified by mass spectrometry. The expression of all genes was detected at the mRNA level by semiquantitative reverse transcription-PCR, and they showed a differential expression at different developmental stages. This is the first time that a fungus is reported to have more than one gene encoding the regulatory subunit of PKA.Filamentous fungi are defined by their ability to form highly polarized hyphae, which is a prerequisite for efficient colonization of growth niches and substrate utilization. During vegetative growth, the establishment of polarity is an important initiation step for primary germ tube emergence from the spore/conidium on the one hand, and branch emergence from existing hyphae on the other. Once established, polarity must be maintained during hyphal extension. Structural components of the cytoskeleton (especially actin) play a pivotal role in establishing and maintaining fungal polar growth (10).One of the key regulators of polarity in fungi, as well as of other processes such as development, mating, and virulence is the cyclic AMP (cAMP)-dependent protein kinase A (PKA) (5,14). This enzyme in its inactive form is a tetramer composed of two regulatory subunits (R) bound to two catalytic subunits (C). In response to signals that increase intracellular cAMP levels, cAMP binds to the regulatory subunit and triggers conformational changes that release the active catalytic subunit. In mammalian systems there are four genes coding for the R subunit-RI␣, RI␤, RII␣, and RII␤-and three genes coding for the C subunit-C␣, C␤, and C␥.In several Ascomycota (Saccharomyces cerevisiae, Candida albicans, Aspergillus niger, Aspergillus nidulans, and Aspergillus fumigatus) and two Basidiomycota (Ustilago maydis and Cryptococcus neoformans) PKA C subunits are coded by two or three genes, whereas only one gene codes for the R subunit. Genetic evidences have shown the participation of PKA in cell polarity in some of these models. Thus, in S. cerevisiae pseudohyphal differentiation was altered by deletion of the gene coding for the ...

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Section: Discussionmentioning

confidence: 99%

A Subunit of Protein Kinase A Regulates Growth and Differentiation in the FungusMucor circinelloides

et al. 2009

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“…Regulation of CHS genes has been shown to occur at the transcriptional and post-transcriptional levels. Transcriptional regulation was reported to take place during the dimorphic transition of Candida albicans [4], Mucor circinelloides [13] and Paracoccidioides brasiliensis [17], where in general mycelial genes were up-regulated. In the present study, we observed slightly higher transcript levels in mycelium, the exception being CHS4.…”

Section: Discussionmentioning

confidence: 99%

“…Taking into consideration the importance of chitin and b-glucans in the construction of the cell wall, and the scant information on the level of regulation of the genes encoding their synthases [4,12,13,18,25] we have proceeded to analyze the transcriptional regulation of the genes encoding chitin and b-1,3-glucan synthases in U. maydis at different developmental stages, under some stress conditions, and during the invasion of its host. This Basidiomycota fungus is a specific pathogen of maize that requires its host to complete the sexual life cycle [for reviews see [5], [11], [22], [26]].…”

Section: Introductionmentioning

confidence: 99%

Transcriptional Regulation of the Genes Encoding Chitin and β-1,3-Glucan Synthases from Ustilago maydis

Robledo-Briones

Ruíz-Herrera

2012

Curr Microbiol

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Transcriptional regulation of genes encoding chitin synthases (CHS) and β-1,3-glucan synthase (GLS) from Ustilago maydis was studied. Transcript levels were measured during the growth curve of yeast and mycelial forms, in response to ionic and osmotic stress, and during infection of maize plants. Expression of the single GLS gene was constitutive. In contrast, CHS genes expression showed differences depending on environmental conditions. Transcript levels were slightly higher in the mycelial forms, the highest levels occurring at the log phase. Ionic and osmotic stress induced alterations in the expression of CHS genes, but not following a defined pattern, some genes were induced and others repressed by the tested compounds. Changes in transcripts were more apparent during the pathogenic process. At early infection stages, only CHS6 gene showed significant transcript levels, whereas at the period of tumor formation CHS7 and CHS8 genes were also were induced.

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“…In other cases regulation occurs during cell differentiation, such as it occurs specifically with CaChs2 mRNA whose levels increase during the dimorphic transition of C. albicans [68]. Also during dimorphism of U. maydis, levels of transcripts of different CHS genes become elevated [69,70], and transcript from CHS1, but not other CHS genes accumulates in the mycelial, but not in the yeast forms of Mucor circinelloides [71]. Transcripts from P. brasiliensis CHS genes were detected in both yeastlike (Y) and mycelial (M) cultures where all exhibited similar patterns of expression during the M to Y transition, with a preferential expression in the M form.…”

Section: Multigenic Control Of Chitin Synthases In Fungimentioning

confidence: 96%

Chitin Synthesis as a Target for Antifungal Drugs

Ruiz-Herrera¹,

San-Blas

2003

CDTID

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Human mycoses have become a threat to health world-wide. Unfortunately there are only a limited number of antimycotic drugs in use. Promising targets for drugs specific against fungi are those affecting chitin synthesis. Chitin is absent in vertebrates, and is essential for fungal wall integrity. A thorough knowledge of the mechanism of chitin synthesis is required to design specific inhibitors. We review here our current understanding of the process, and the most promising drugs that inhibit it. Chitin is made by chitin synthases requiring specific microvesicles, the chitosomes, for intracellular transport. Fungi contain several chitin synthases, some of which may be essential at a certain stage. This phenomenon is important to take into account for drug design. The most widely studied chitin synthase inhibitors are polyoxins and nikkomycins that probably bind to the catalytic site of chitin synthases. These are not equally susceptible to the drugs. In Saccharomyces cerevisiae the order of sensitivity is: Chs3p>Chs1p>Chs2p. Main problems for their succesful use in vivo are: low permeability, and different susceptibility of fungal species, and variable responses in animal models. Chemical modifications have been proposed to make more potent derivatives. Other synthetic or natural compounds are also promising as possible inhibitors, but their properties are less well known. Rational drug design has proceeded only on the basis of existing inhibitors, because the structure of the active site of chitin synthase is unknown. Undoubtedly, determination of this, and the biosynthetic mechanism will reveal unexpected drug targets in the future.

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Mcchs1 , a Member of a Chitin Synthase Gene Family in Mucor circinelloides , Is Differentially Expressed During Dimorphism

Cited by 14 publications

References 32 publications

A Subunit of Protein Kinase A Regulates Growth and Differentiation in the FungusMucor circinelloides

A Subunit of Protein Kinase A Regulates Growth and Differentiation in the FungusMucor circinelloides

Transcriptional Regulation of the Genes Encoding Chitin and β-1,3-Glucan Synthases from Ustilago maydis

Chitin Synthesis as a Target for Antifungal Drugs

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