TY  - JOUR
A1  - Mottola, Austin
A1  - Morschhäuser, Joachim
T1  - An intragenic recombination event generates a Snf4-independent form of the essential protein kinase SNF1 in Candida albicans
JF  - mSphere
N2  - The heterotrimeric protein kinase SNF1 plays a key role in the metabolic adaptation of the pathogenic yeast Candida albicans. It consists of the essential catalytic α-subunit Snf1, the γ-subunit Snf4, and one of the two β-subunits Kis1 and Kis2. Snf4 is required to release the N-terminal catalytic domain of Snf1 from autoinhibition by the C-terminal regulatory domain, and snf4Δ mutants cannot grow on carbon sources other than glucose. In a screen for suppressor mutations that restore growth of a snf4Δ mutant on alternative carbon sources, we isolated a mutant in which six amino acids between the N-terminal kinase domain and the C-terminal regulatory domain of Snf1 were deleted. The deletion was caused by an intragenic recombination event between two 8-bp direct repeats flanking six intervening codons. In contrast to truncated forms of Snf1 that contain only the kinase domain, the Snf4-independent Snf1\(^{Δ311 − 316}\) was fully functional and could replace wild-type Snf1 for normal growth, because it retained the ability to interact with the Kis1 and Kis2 β-subunits via its C-terminal domain. Indeed, the Snf4-independent Snf1\(^{Δ311 − 316}\) still required the β-subunits of the SNF1 complex to perform its functions and did not rescue the growth defects of kis1Δ mutants. Our results demonstrate that a preprogrammed in-frame deletion event within the SNF1 coding region can generate a mutated form of this essential kinase which abolishes autoinhibition and thereby overcomes growth deficiencies caused by a defect in the γ-subunit Snf4.
KW  - AMP-activated kinases
KW  - Candida albicans
KW  - genetic recombination
KW  - metabolic adaptation
KW  - suppressor mutation
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202170
VL  - 4
IS  - 3
ER  - 
TY  - JOUR
A1  - Popp, Christina
A1  - Ramírez-Zavala, Bernardo
A1  - Schwanfelder, Sonja
A1  - Krüger, Ines
A1  - Morschhäuser, Joachim
T1  - Evolution of fluconazole-resistant Candida albicans strains by drug-induced mating competence and parasexual recombination
JF  - mBio
N2  - The clonal population structure of Candida albicans suggests that (para)sexual recombination does not play an important role in the lifestyle of this opportunistic fungal pathogen, an assumption that is strengthened by the fact that most C. albicans strains are heterozygous at the mating type locus (MTL) and therefore mating-incompetent. On the other hand, mating might occur within clonal populations and allow the combination of advantageous traits that were acquired by individual cells to adapt to adverse conditions. We have investigated if parasexual recombination may be involved in the evolution of highly drug-resistant strains exhibiting multiple resistance mechanisms against fluconazole, an antifungal drug that is commonly used to treat infections by C. albicans. Growth of strains that were heterozygous for MTL and different fluconazole resistance mutations in the presence of the drug resulted in the emergence of derivatives that had become homozygous for the mutated allele and the mating type locus and exhibited increased drug resistance. When MTLa/a and MTLα/α cells of these strains were mixed in all possible combinations, we could isolate mating products containing the genetic material from both parents. The initial mating products did not exhibit higher drug resistance than their parental strains, but further propagation under selective pressure resulted in the loss of the wild-type alleles and increased fluconazole resistance. Therefore, fluconazole treatment not only selects for resistance mutations but also promotes genomic alterations that confer mating competence, which allows cells in an originally clonal population to exchange individually acquired resistance mechanisms and generate highly drug-resistant progeny.
KW  - Candida albicans
KW  - drug resistance evolution
KW  - mating
KW  - parasexual recombination
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-200901
VL  - 10
IS  - 1
ER  -