Localization and activity of the calcineurin catalytic and regulatory subunit complex at the septum is essential for hyphal elongation and proper septation in Aspergillus fumigatus

Praveen Rao Juvvadi, Jarrod Fortwendel, Luise E. Rogg, Kimberlie A. Burns, Scott H. Randell, William J. Steinbach

Research output: Contribution to journalArticle

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Abstract

Calcineurin, a heterodimer composed of the catalytic (CnaA) and regulatory (CnaB) subunits, plays key roles in growth, virulence and stress responses of fungi. To investigate the contribution of CnaA and CnaB to hyphal growth and septation, ΔcnaB and ΔcnaAΔcnaB strains of Aspergillus fumigatus were constructed. CnaA colocalizes to the contractile actin ring early during septation and remains at the centre of the mature septum. While CnaB's septal localization is CnaA-dependent, CnaA's septal localization is CnaB-independent, but CnaB is required for CnaA's function at the septum. Catalytic null mutations in CnaA caused stunted growth despite septal localization of the calcineurin complex, indicating the requirement of calcineurin activity at the septum. Compared to the ΔcnaA and ΔcnaB strains, the ΔcnaAΔcnaB strain displayed more defective growth and aberrant septation. While three Ca 2+-binding motifs in CnaB were sufficient for its association with CnaA at the septum, the amino-terminal arginine-rich domains (16-RRRR-19 and 44-RLRKR-48) are dispensable for septal localization, yet required for complete functionality. Mutation of the 51-KLDK-54 motif in CnaB causes its mislocalization from the septum to the nucleus, suggesting it is a nuclear export signal sequence. These findings confirm a cooperative role for the calcineurin complex in regulating hyphal growth and septation.

Original languageEnglish (US)
Pages (from-to)1235-1259
Number of pages25
JournalMolecular Microbiology
Volume82
Issue number5
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

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Aspergillus fumigatus
Calcineurin
Catalytic Domain
Growth
Nuclear Export Signals
Growth Disorders
Mutation
Protein Sorting Signals
Virulence
Arginine
Actins
Fungi

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Microbiology

Cite this

Localization and activity of the calcineurin catalytic and regulatory subunit complex at the septum is essential for hyphal elongation and proper septation in Aspergillus fumigatus. / Juvvadi, Praveen Rao; Fortwendel, Jarrod; Rogg, Luise E.; Burns, Kimberlie A.; Randell, Scott H.; Steinbach, William J.

In: Molecular Microbiology, Vol. 82, No. 5, 01.12.2011, p. 1235-1259.

Research output: Contribution to journalArticle

Juvvadi, Praveen Rao ; Fortwendel, Jarrod ; Rogg, Luise E. ; Burns, Kimberlie A. ; Randell, Scott H. ; Steinbach, William J. / Localization and activity of the calcineurin catalytic and regulatory subunit complex at the septum is essential for hyphal elongation and proper septation in Aspergillus fumigatus. In: Molecular Microbiology. 2011 ; Vol. 82, No. 5. pp. 1235-1259.
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