Molecular Dissection of Alleles of the osmotic-1 Locus of Neurospora crassa

Miller, Tamara; Renault, Samantha; Selitrennikoff, Claude P.

doi:10.1006/fgbi.2001.1306

Cited by 45 publications

(53 citation statements)

References 46 publications

(88 reference statements)

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“…The pathway has been characterized most completely in yeast (O'Rourke et al, 2002), and is found in numerous fungal species on the basis of comparative genomics (Krantz et al, 2006). In N. crassa, a histidine kinase sensor OS-1 (Alex et al, 1996;Miller et al, 2002) and an associated response regulator RRG-1 (Jones et al, 2007) function upstream of the MAPKKK OS-4 and MAPKK OS-5 (Fujimura et al, 2003), and MAPK OS-2 (Zhang et al, 2002), to elicit both glycerol accumulation (Noguchi et al, 2007) and ion accumulation (Lew et al, 2006) during turgor recovery after hyperosmotic shock.…”

Section: Introductionmentioning

confidence: 99%

Transient responses during hyperosmotic shock in the filamentous fungus Neurospora crassa

Lew

Nasserifar

2009

Microbiology

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Fungal cells maintain an internal hydrostatic pressure (turgor) of about 400-500 kPa. In the filamentous fungus Neurospora crassa, the initial cellular responses to hyperosmotic treatment are loss of turgor, a decrease in relative hyphal volume per unit length (within 1 min) and cell growth arrest; all recover over a period of 10-60 min due to increased net ion uptake and glycerol production. The electrical responses to hyperosmotic treatment are a transient depolarization of the potential (within 1 min), followed by a sustained hyperpolarization (after 4 min) to a potential more negative than the initial potential (a driving force for ion uptake). The nature of the transient depolarization was explored in the context of other transient responses to hyperosmotic shock, to determine whether activation of a specific ion permeability or some other rapid change in electrogenic transport was responsible. Changing the ionic composition of the extracellular medium revealed that K + permeability increases and H + permeability declines during the transient depolarization. We suggest that these changes are due to concerted inhibition of the electrogenic H + -ATPase, and an increase in a K + conductance. Knockout mutants of known K + (tok, trk, trm-8, hak-1) and Cl " (a clc-3 homologue) channels and transporters had no effect on the transient depolarization, but trk and hak-1 do play a role in osmoadaptation, as does a homologue of a serine kinase regulator of H + -ATPase in yeast, Ptk2.

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Section: Introductionmentioning

confidence: 99%

Transient responses during hyperosmotic shock in the filamentous fungus Neurospora crassa

Lew

Nasserifar

2009

Microbiology

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“…As per the SMART database Nik1 orthologs from yeast contain five HAMP domains, whereas those from filamentous ascomycetes and basidiomycetes contain six and seven HAMP domains, respectively (14). Point mutations in the HAMP domains have been shown to affect fludioxonil sensitivity as well as osmosensing functions of Nik1 orthologs (8,15,16). The poly-HAMP module plays a very important role in the functionality of the group III HHK and appears to function both as sensor and regulator of its activity.…”

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confidence: 99%

Differential Role of HAMP-like Linkers in Regulating the Functionality of the Group III Histidine Kinase DhNik1p

Kaur

Singh

Rathore

et al. 2014

Journal of Biological Chemistry

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“…Two lines of evidence led us to believe that they may be importance for osmosensing by DhNik1p. First, several osmosensitive and fungicide-resistant mutants were identified that carried point mutations in HAMP domain repeat in Nik1 orthologs (17,26,27). Second, we have observed that a chimeric construct where the N-terminal nonkinase region (which is essential for its membrane localization and osmosensing) of DhSln1p (a Sln1p ortholog in D. hansenii) was swapped with the N-terminal region of DhNik1p containing HAMP repeats could also complement sln1 mutation in S. cerevisiae.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, they have a unique N-terminal region consisting of HAMP domain repeats. The analysis of the fungicide-resistant field or laboratory isolates of N. crassa, B. cinerea, and Cochliobolus heterostrophus showed that many of these mutants harbor point mutations in the HAMP domain repeats of the respective Nik1 orthologs and therefore suggested that these repeats are functionally very important (17,26,27). HAMP domains are so named because of their frequent occurrence in proteins associated with signal transduction in prokaryotic and lower eukaryotic organisms, such as histidine kinases, adenyl cyclases, methyl accepting chemotaxis proteins and phosphatases (28).…”

mentioning

confidence: 99%

Interactions among HAMP Domain Repeats Act as an Osmosensing Molecular Switch in Group III Hybrid Histidine Kinases from Fungi

Meena

Kaur

Mondal

2010

Journal of Biological Chemistry

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The members of group III hybrid histidine kinases (HHK) are ubiquitous in fungi. Group III HHK have been implicated to function as osmosensors in the high osmolarity glycerol (HOG) pathway that is essential for fungal survival under high osmolarity stress. Recent literature suggests that group III HHK are also involved in conidia formation, virulence in several filamentous fungi, and are an excellent molecular target for antifungal agents. Thus, group III HHK constitute a very important group of sensor kinases. Structurally, group III HHK are distinct from Sln1p, the osmosensing HHK that regulates the HOG pathway in Saccharomyces cerevisiae. Group III HHK lack any transmembrane domain and typically contain HAMP domain repeats at the N terminus. Until now, it is not clear how group III HHK function as an osmosensor to regulate the HOG pathway. To investigate this, we undertook molecular characterization of DhNIK1, an ortholog from osmotolerant yeast Debaryomyces hansenii. We show here that DhNIK1 could complement sln1 mutation in S. cerevisiae thereby confirming its role as a bona fide osmosensor. We further investigated the role of HAMP domains by deleting them systematically. Our results clearly indicate that the HAMP4 domain is crucial for osmosensing by DhNik1p. Most importantly, we also show that the alternative interaction among the HAMP domains regulates the activity of DhNik1p like an "on-off switch" and thus provides, for the first time, an insight into the molecular mechanism of osmosensing by this group of HHKs.

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Molecular Dissection of Alleles of the osmotic-1 Locus of Neurospora crassa

Cited by 45 publications

References 46 publications

Transient responses during hyperosmotic shock in the filamentous fungus Neurospora crassa

Transient responses during hyperosmotic shock in the filamentous fungus Neurospora crassa

Differential Role of HAMP-like Linkers in Regulating the Functionality of the Group III Histidine Kinase DhNik1p

Interactions among HAMP Domain Repeats Act as an Osmosensing Molecular Switch in Group III Hybrid Histidine Kinases from Fungi

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