The polarisome component SPA-2 localizes at the apex of Neurospora crassa and partially colocalizes with the Spitzenkorper
The polarisome component SPA-2 localizes at the apex of Neurospora crassa and partially colocalizes with the Spitzenkorper
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DOI：
10.1016/j.fgb.2009.02.009
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发表时间：
2009-08-01
影响因子：
3
通讯作者：
Castro-Longoria, Ernestina
中科院分区：
文献类型：
--
作者：
Araujo-Palomares, Cynthia L.;Riquelme, Meritxell;Castro-Longoria, Ernestina
In fungal hyphae multiple protein complexes assemble at sites of apical growth to maintain cell polarity and promote nucleation of actin. Polarity allows the directional traffic of vesicles to the Spitzenkorper (Spk) prior to fusing with the plasma membrane to provide precursors and enzymes required for cell extension and nutrition. One of these complexes is the polarisome, which in Saccharomyces cerevisiae contains Spa2p, Pea2p, Bud6p/Aip3p and Bni1p. To investigate the localization and role of the polarisome during Spk establishment in Neurospora crassa we tagged SPA-2 with the green fluorescent protein (GFP) and examined growing cells by laser scanning confocal microscopy in elongating germ tubes and mature hyphae. SPA-2-GFP accumulated gradually at the apex of germ tubes, when a FM4-64 stained Spk was not still detectable. When the germlings reached about 40 mu m in length, a FM4-64 stained Spk started to be apparent and from this point on SPA-2-GFP was observed in the apical region of both germ tubes and mature hyphae, as a hand fan shape with a brighter spot at the base. Fusion of the N. crassa SPA-2-GFP strain with a N. crassa strain expressing chitin synthase 1 (CHS-1) labeled with mCherryFP indicated only partial colocalization of the polarisome and the Spk core. N. crassa SPA-2-GFP was also found at the apex of forming branches but not in septa, suggesting that it participates only in areas of tip growth. A Delta spa-2 strain displayed hyphae with uneven constrictions, apices with an unstable Spk, reduced growth rate and higher number of branches than the wild type strain, indicating that SPA-2 is required for the stability, behavior and morphology of the Spk and maintenance of regular apical growth in hyphae of N. crassa, although not for polarity or Spk establishment. (C) 2009 Elsevier Inc. All rights reserved.
