Two divergent plasma membrane syntaxin-like SNAREs, nsyn1 and nsyn2, contribute to hyphal tip growth and other developmental processes in Neurospora crassa.
Highly polarized exocytosis of vesicles at hyphal apices is an essential requirement of tip growth. This requirement may be met by the localization and/or activation of an apical SNARE-based machinery. We have cloned nsyn1 and nsyn2, SNAREs predicted to function at the plasma membrane in Neurospora crassa. Transformation of extra copies of nsyn1 into wild-type strains displayed effects consistent with quelling of nsyn1 expression, which was lethal in most transformants. All surviving transformants grew slowly, conidiated poorly, and were male sterile. In addition, antisense nsyn1 strains grew slowly, with abnormal hyphal diameters and polarity and defective conidiation. For nsyn2, several repeat induced point mutation (RIP) crosses produced no, or poorly germinating ascospores. Those that germinated produced slow-growing hyphae with abnormal branching. The defects in nsyn1 and nsyn2 mutants are consistent with differential impaired vesicle fusion in hyphal tips and other developmental stages.
Department of Biology, York University, 4700 Keele Street, Ont., M3J1P3, Toronto, Canada. gagan@ncbs.res.in
Gagan D
GD
Gupta
Stephen J
SJ
Free
Natalia N
NN
Levina
Sirkka
S
Keränen
I Brent
IB
Heath
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D005656:Fungal Proteins / Q000235:genetics*; D005816:Genetic Complementation Test; D005838:Genotype; D006801:Humans; D025301:Hyphae / Q000254:growth & development*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development; D010957:Plasmids; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins
D017931:DNA Primers; D005656:Fungal Proteins; D008565:Membrane Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins