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Gagan D Gupta

Publications and source records attributed to Gagan D Gupta.

5 recordsLinked to original sources
PubMed2005

Co-expressed recombinant human Translin-Trax complex binds DNA.

Trax, expressed alone aggregates into insoluble complexes, whereas upon co-expression with Translin becomes readily soluble and forms a stable heteromeric complex ( approximately 430 kDa) containing both proteins at nearly equimolar ratio. Based on the subunit molecular weights, estimated by MALDI-TOF-MS, the purified complex appears to comprise of either an octameric Translin plus a hexameric Trax (calculated MW 420 kDa) or a heptamer each of Trax and Translin (calculated MW 425 kDa) or a hexameric Translin plus an octameric Trax (calculated MW 431 kDa). The complex binds single-stranded/double-stranded DNA. ssDNA gel-shifted complex shows both proteins at nearly equimolar ratio, suggesting that Translin "chaperones" Trax and forms heteromeric complex that is DNA binding competent.

DNA↗
PubMed2003

The interrelationships of actin and hyphal tip growth in the ascomycete Geotrichum candidum.

Geotrichum candidum is unusual among reported hyphal ascomycetes in that its hyphae readily stain with phalloidin to reveal actin concentrated in the Spitzenkörper (SPK) and plaques associated with the plasma membrane (PM). Loss of SPK actin, but not the PM plaques, following latrunculin B treatment produces tip swelling, consistent with actin restraining tip morphology or localizing vesicle exocytosis. Tip morphogenesis may also involve a spectrin-like protein which concentrates at the apical PM in plaques unassociated with the actin plaques. Branch formation occurs with growth rates initially about 20% those of leading tips, and does not involve a morphologically detectable SPK, nor SPK-like actin ensembles, indicating the dispensibility of this structure in tip growth. Surprisingly, new tubular tips can form in the continued presence of latrunculin, consistent with alternative cellular systems, such as the spectrin-like protein, substituting for actin's critical functions.

Actins↗
PubMed2003

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.

Amino Acid Sequence↗
PubMed2002

Predicting the distribution, conservation, and functions of SNAREs and related proteins in fungi.

Hyphal tip growth, the hallmark of the fungi, requires highly polarized and localized exocytosis, but how this requirement is met is unknown. Members of conserved protein families called SNAREs and Rabs mediate vesicle trafficking and fusion at virtually every step of the intracellular pathway in all examined eukaryotes. We have searched the available nearly complete fungal genomes, established the presence or absence of members of the SNARE and Rab families in these genomes, and predicted their evolutionary relationships to one another. Comparisons with the extensively studied Saccharomyces cerevisiae indicate that, in general, most of the members of these families (including those involved in mediating exocytosis) are conserved. The presence of exceptional SNAREs and Rabs in some fungi that are not conserved in S. cerevisiae may be indicative of specialized steps that occur in these fungi. The implications of these findings for current tip growth models are discussed.

Amino Acid Sequence↗