Photo of John Vierula

John Vierula

Associate Professor

Degrees:B.Sc. (York), Ph.D. (Calgary), Post Doc (Guelph)
Phone:613-520-2600 x 7519
Email:john_vierula@carleton.ca
Office:246 Nesbitt Building

Research

Filamentous fungi such as Neurospora crassa grow by apical extension of hyphal tip cells. Perturbations in any of the processes required for tip growth are readily apparent since they result in an aberrant colony morphology. To learn more about the molecular biology of tip growth, we are cloning genes which are required for normal colony morphology. In addition to standard cloning and sequence analysis, we use microscopy and a variety of biochemical approaches to deduce the function of the products of these genes. For example, one group of morphological mutants known as ropy have defective nuclear migration in their hyphae. One of the genes we have analysed, ropy-4, encodes an actin-related protein (centractin) which is part of the dynactin activating complex for the microtubule-based motor protein known as cytoplasmic dynein. The ropy-2 gene codes for p62, a centractin capping protein of the dynactin/dynein motor assembly. Another interesting mutant strain (cot-3), which forms small colonies at elevated temperatures, has a mutation in the gene encoding elongation factor 2 (EF-2).

Fungal Cell Wall Structure

Although fungal cell walls mainly consist of layers of modified sugar chains, they also contain an assortment of different proteins. We are using liquid chromatography tandem mass spectrometry (LC MS/MS) to identify these proteins as a first step in deducing their function. In addition to the discovery of several novel proteins, the results of these studies suggest that common cytoplasmic proteins such as glycolytic enzymes, heat shock proteins and ribosomal proteins are also components of the cell wall. We are currently testing the hypothesis that some of these enzymes have an additional role in cell wall biogenesis or stabilization.

Selected Publications

Propheta O, Vierula J, Toporowski P, Gorovits R and Yarden O 2001 The N. crassa colonial temperature sensitive 3 (cot-3) gene encodes protein elongation factor 2. Mol Gen Genet. 264:894-901.

Vierula PJ and Mais JM 1997 A gene required for nuclear migration in Neurospora crassa codes for a protein with cysteine-rich, LIM/RING-like domains. Molecular Microbiology 24: 331-340.

Vierula PJ 1997 Cloning and characterization of a Neurospora crassa ribosomal protein gene, crps-7. Current Genetics 31: 139-143.

Robb MJ, Wilson MA and Vierula PJ 1995 A fungal actin-related protein involved in nuclear migration. Molecular and General Genetics 247: 583-590.

Pu RT, Xu, G., Wu G, Vierula, J , O’Donnell K, Ye XS and Osmani SA 1995 Isolation of a functional homolog of the cell cycle-specific NIMA protein kinase of Aspergillus nidulans and functional analysis of conserved residues. J. of Biol. Chem 270: 18110-18116.

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