scholarly journals Genome-wide analysis of maltose utilization and regulation in aspergilli

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 3893-3902 ◽  
Author(s):  
Wanwipa Vongsangnak ◽  
Margarita Salazar ◽  
Kim Hansen ◽  
Jens Nielsen
Keyword(s):  
Regulatory Protein ◽  
Regulatory System ◽  
Industrial Fermentation ◽  
Maltose Permease ◽  
Fermentation Processes ◽  
Cellular Physiology ◽  
Maltose Transport ◽  
Genome Wide ◽  
Major Route ◽  
Maltose Utilization

Maltose utilization and regulation in aspergilli is of great importance for cellular physiology and industrial fermentation processes. In Aspergillus oryzae, maltose utilization requires a functional MAL locus, composed of three genes: MALR encoding a regulatory protein, MALT encoding maltose permease and MALS encoding maltase. Through a comparative genome and transcriptome analysis we show that the MAL regulon system is active in A. oryzae while it is not present in Aspergillus niger. In order to utilize maltose, A. niger requires a different regulatory system that involves the AmyR regulator for glucoamylase (glaA) induction. Analysis of reporter metabolites and subnetworks illustrates the major route of maltose transport and metabolism in A. oryzae. This demonstrates that overall metabolic responses of A. oryzae occur in terms of genes, enzymes and metabolites when the carbon source is altered. Although the knowledge of maltose transport and metabolism is far from being complete in Aspergillus spp., our study not only helps to understand the sugar preference in industrial fermentation processes, but also indicates how maltose affects gene expression and overall metabolism.

scholarly journals Characterization and Functional Analysis of the MAL and MPH Loci for Maltose Utilization in Some Ale and Lager Yeast Strains

2005 ◽  
Vol 71 (12) ◽  
pp. 7846-7857 ◽  
Author(s):  
Virve Vidgren ◽  
Laura Ruohonen ◽  
John Londesborough
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Lager Yeast ◽  
Maltose Permease ◽  
Maltose Transport ◽  
Yeast Strains ◽  
Maltose Utilization ◽  
Low Levels ◽  
Brewer’S Yeasts ◽  
Broad Specificity

ABSTRACT Maltose and maltotriose are the major sugars in brewer's wort. Brewer's yeasts contain multiple genes for maltose transporters. It is not known which of these express functional transporters. We correlated maltose transport kinetics with the genotypes of some ale and lager yeasts. Maltose transport by two ale strains was strongly inhibited by other α-glucosides, suggesting the use of broad substrate specificity transporters, such as Agt1p. Maltose transport by three lager strains was weakly inhibited by other α-glucosides, suggesting the use of narrow substrate specificity transporters. Hybridization studies showed that all five strains contained complete MAL1, MAL2, MAL3, and MAL4 loci, except for one ale strain, which lacked a MAL2 locus. All five strains also contained both AGT1 (coding a broad specificity α-glucoside transporter) and MAL11 alleles. MPH genes (maltose permease homologues) were present in the lager but not in the ale strains. During growth on maltose, the lager strains expressed AGT1 at low levels and MALx1 genes at high levels, whereas the ale strains expressed AGT1 at high levels and MALx1 genes at low levels. MPHx expression was negligible in all strains. The AGT1 sequences from the ale strains encoded full-length (616 amino acid) polypeptides, but those from both sequenced lager strains encoded truncated (394 amino acid) polypeptides that are unlikely to be functional transporters. Thus, despite the apparently similar genotypes of these ale and lager strains revealed by hybridization, maltose is predominantly carried by AGT1-encoded transporters in the ale strains and by MALx1-encoded transporters in the lager strains.

Repeated Family of Genes Controlling Maltose Fermentation in Saccharomyces carlsbergensis

1983 ◽  
Vol 3 (5) ◽  
pp. 796-802
Author(s):  
Richard B. Needleman ◽  
Corinne Michels
Keyword(s):  
Genetic Analysis ◽  
Structural Gene ◽  
Regulatory Gene ◽  
Regulatory Protein ◽  
Physical Analysis ◽  
Saccharomyces Carlsbergensis ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
Complex Locus ◽  
Dna Fragment

Maltose fermentation in Saccharomyces spp. requires the presence of any one of five unlinked genes: MAL1, MAL2, MAL3, MAL4 , or MAL6. Although the genes are functionally equivalent, their natures and relationships to each other are not known. At least three proteins are necessary for maltose fermentation: maltase, maltose permease, and a regulatory protein. The MAL genes may code for one or more of these proteins. Recently a DNA fragment containing a maltase structural gene has been cloned from a MAL6 strain, CB11, to produce plasmid pMAL9-26. We have conducted genetic and physical analyses of strain CB11. The genetic analysis has demonstrated the presence of two cryptic MAL genes in CB11, MAL1g and MAL3g (linked to MAL1 and to MAL3 , respectively), in addition to the MAL6 locus. The physical analysis, which used a subclone of plasmid pMAL9-26 as a probe, detected three Hin dIII genomic fragments with homology to the probe. Each fragment was shown to be linked to one of the MAL loci genetically demonstrated to be present in CB11. Our results indicate that the cloned maltase structural gene in plasmid pMAL9-26 is linked to MAL6. Since the MAL6 locus has previously been shown to contain a regulatory gene, the MAL6 locus must be a complex locus containing at least two of the factors needed for maltose fermentation: the structural gene for maltase and the maltase regulatory protein. The absence of other fragments which hybridize to the MAL6 -derived probe shows that either MAL2 and MAL4 are not related to MAL6 , or the DNA corresponding to these genes is absent from the MAL6 strain CB11.

scholarly journals Intracellular Maltose Is Sufficient To Induce MAL Gene Expression in Saccharomyces cerevisiae

2002 ◽  
Vol 1 (5) ◽  
pp. 696-703 ◽  
Author(s):  
Xin Wang ◽  
Mehtap Bali ◽  
Igor Medintz ◽  
Corinne A. Michels
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Plantago Major ◽  
Null Mutant ◽  
Transport Activity ◽  
Maltose Permease ◽  
Maltose Transport ◽  
Constitutive Overexpression ◽  
Reduced Rate

ABSTRACT The presence of maltose induces MAL gene expression in Saccharomyces cells, but little is known about how maltose is sensed. Strains with all maltose permease genes deleted are unable to induce MAL gene expression. In this study, we examined the role of maltose permease in maltose sensing by substituting a heterologous transporter for the native maltose permease. PmSUC2 encodes a sucrose transporter from the dicot plant Plantago major that exhibits no significant sequence homology to maltose permease. When expressed in Saccharomyces cerevisiae, PmSUC2 is capable of transporting maltose, albeit at a reduced rate. We showed that introduction of PmSUC2 restores maltose-inducible MAL gene expression to a maltose permease-null mutant and that this induction requires the MAL activator. These data indicate that intracellular maltose is sufficient to induce MAL gene expression independently of the mechanism of maltose transport. By using strains expressing defective mal61 mutant alleles, we demonstrated a correlation between the rate of maltose transport and the level of the induction, which is particularly evident in medium containing very limiting concentrations of maltose. Moreover, our results indicate that a rather low concentration of intracellular maltose is needed to trigger MAL gene expression. We also showed that constitutive overexpression of either MAL61 maltose permease or PmSUC2 suppresses the noninducible phenotype of a defective mal13 MAL-activator allele, suggesting that this suppression is solely a function of maltose transport activity and is not specific to the sequence of the permease. Our studies indicate that maltose permease does not function as the maltose sensor in S. cerevisiae.

A systematic approach for scaling Aspergillus niger industrial fermentation processes

2012 ◽  
Vol 29 ◽  
pp. S13
Author(s):  
Margarita Salazar Pena ◽  
Morten S. Hansen ◽  
Stuart M. Stocks
Keyword(s):  
Aspergillus Niger ◽  
Systematic Approach ◽  
Industrial Fermentation ◽  
Fermentation Processes

scholarly journals Repeated Family of Genes Controlling Maltose Fermentation inSaccharomyces carlsbergensis

1983 ◽  
Vol 3 (5) ◽  
pp. 796-802 ◽  
Author(s):  
Richard B. Needleman ◽  
Corinne Michels
Keyword(s):  
Genetic Analysis ◽  
Structural Gene ◽  
Regulatory Gene ◽  
Regulatory Protein ◽  
Physical Analysis ◽  
Maltose Permease ◽  
Maltose Fermentation ◽  
Complex Locus ◽  
Dna Fragment

Maltose fermentation inSaccharomycesspp. requires the presence of any one of five unlinked genes:MAL1, MAL2, MAL3, MAL4, orMAL6.Although the genes are functionally equivalent, their natures and relationships to each other are not known. At least three proteins are necessary for maltose fermentation: maltase, maltose permease, and a regulatory protein. TheMALgenes may code for one or more of these proteins. Recently a DNA fragment containing a maltase structural gene has been cloned from aMAL6strain, CB11, to produce plasmid pMAL9-26. We have conducted genetic and physical analyses of strain CB11. The genetic analysis has demonstrated the presence of two crypticMALgenes in CB11,MAL1gandMAL3g(linked toMAL1and toMAL3, respectively), in addition to theMAL6locus. The physical analysis, which used a subclone of plasmid pMAL9-26 as a probe, detected threeHindIII genomic fragments with homology to the probe. Each fragment was shown to be linked to one of theMALloci genetically demonstrated to be present in CB11. Our results indicate that the cloned maltase structural gene in plasmid pMAL9-26 is linked toMAL6.Since theMAL6locus has previously been shown to contain a regulatory gene, theMAL6locus must be a complex locus containing at least two of the factors needed for maltose fermentation: the structural gene for maltase and the maltase regulatory protein. The absence of other fragments which hybridize to theMAL6-derived probe shows that eitherMAL2andMAL4are not related toMAL6, or the DNA corresponding to these genes is absent from theMAL6strain CB11.

scholarly journals RocA Binds CsrS To Modulate CsrRS-Mediated Gene Regulation in Group A Streptococcus

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Nicola N. Lynskey ◽  
Jorge J. Velarde ◽  
Meredith B. Finn ◽  
Simon L. Dove ◽  
Michael R. Wessels
Keyword(s):  
Gene Regulation ◽  
Target Genes ◽  
Response Regulator ◽  
Critical Role ◽  
Regulatory Protein ◽  
Regulatory System ◽  
Fine Tuning ◽  
Human Pathogen ◽  
Two Component ◽  
Group A

ABSTRACT The orphan regulator RocA plays a critical role in the colonization and pathogenesis of the obligate human pathogen group A Streptococcus. Despite multiple lines of evidence supporting a role for RocA as an auxiliary regulator of the control of virulence two-component regulatory system CsrRS (or CovRS), the mechanism of action of RocA remains unknown. Using a combination of in vitro and in vivo techniques, we now find that RocA interacts with CsrS in the streptococcal membrane via its N-terminal region, which contains seven transmembrane domains. This interaction is essential for RocA-mediated regulation of CsrRS function. Furthermore, we demonstrate that RocA forms homodimers via its cytoplasmic domain. The serotype-specific RocA truncation in M3 isolates alters this homotypic interaction, resulting in protein aggregation and impairment of RocA-mediated regulation. Taken together, our findings provide insight into the molecular requirements for functional interaction of RocA with CsrS to modulate CsrRS-mediated gene regulation. IMPORTANCE Bacterial two-component regulatory systems, comprising a membrane-bound sensor kinase and cytosolic response regulator, are critical in coordinating the bacterial response to changing environmental conditions. More recently, auxiliary regulators which act to modulate the activity of two-component systems, allowing integration of multiple signals and fine-tuning of bacterial responses, have been identified. RocA is a regulatory protein encoded by all serotypes of the important human pathogen group A Streptococcus. Although RocA is known to exert its regulatory activity via the streptococcal two-component regulatory system CsrRS, the mechanism by which it functions was unknown. Based on new experimental evidence, we propose a model whereby RocA interacts with CsrS in the streptococcal cell membrane to enhance CsrS autokinase activity and subsequent phosphotransfer to the response regulator CsrR, which mediates transcriptional repression of target genes.

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