XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
83.
DELETION of GLUTamaTE DECarBOXYLaSE GENE frOM trICHODErma
virIDE F-534 STraIN
Ľuboš Nižnanský, Svetlana Kryštofova and Ľudovít Varečka
Department of biochemistry and microbiology, Faculty chemical and food technology
Enzyme glutamate decarboxylase (GAD) is present in eukaryotic and prokaryotic organisms,
where is playing role in different processes. GAD catalyses the conversion of L-glutamate
to a non-coded amino acid 4-aminobutyrate (GABA). In yeasts, GAD is important for
oxidative stress response to acid environment. In this study, we used electroporation
to transfer the gad gene disruption cassette with hygromycin resistance into T. viride
conidia and obtained 21 transformants. Deletion of gad gene was proved by GAD activity
measurements and Southern analysis in two transformants (mutants 10 and 21). Mutants
lacking GAD have delayed conidiation. Submerged mycelia formed pellet-shaped mycelia
during submerged cultivation unlike of wild strain. Microscopic analysis of Δgad10
and Δgad21 mutants revealed the increase in forming chlamydospores and thinning of
hyphae. In submerged cultivation with sucrose as carbon source, growth rates of these
mutants were lower than that of wild-type strain, while the growth on GABA as a carbon
source showed the opposite pattern. Growth of Δgad10 was more rapid than that of the
wild-type strain using GABA as carbon source but L-glutamate had an opposite effect.
Respiratory quotients of these mutants were higher than that of wild-type strain. Thus,
the gad gene seems to influence basic bioenergetic processes in this fungus with the
impact on growth and conidiation.
Acknowledgement: This work was supported by grant APVV nr. 0642-07
206 XXII. Biochemistry Congress, Martin