Anchorage of Candida albicans Ssr1 to the cell wall, and transcript profiling of the null mutant.
Incorporation into the wall of Candida albicans Ssr1, a GPI-dependent protein, was investigated by construction of different truncated genes for which the three potential omega sites (S199, S215 and G216) and the corresponding omega+1 and omega+2 were eliminated or modified. Cells of the C. albicans ssr1Delta mutant were transformed with pADH-pl harboring the truncated versions of CaSSR1, pADH-DeltaCaSSR1t(217-234) (lacking a C-terminal hydrophobic stretch of 18 aa including the putative omega+2 and omega+1, omega+2 of S215 and G216) or pADH-DeltaCaSSR1t(199-201) (lacking three serine residues), and their walls were analyzed for the protein. Results suggested that the three serine residues are essential for incorporation of CaSsr1 into the wall beta-glucan. This interpretation was confirmed when the truncated protein CaSsr1pt(199-201) was found in the spent medium. The transcription profile of the 6039 genes in C. albicans ssr1Delta showed that seven genes are upregulated (1.4-fold), including SRP54 (a signal recognition particle subunit), IPF29 (a zinc finger protein) and PTR3 (a transcriptional regulator), whereas 27 genes are downregulated (0.7-fold), including IPF6318 (a beta-glucosidase) and SOU1 (a sorbitol utilization protein). Additional genes showed a reduced increase, or decreased expression, suggesting that some current orphan genes may have unknown cell wall functions. In addition, a compensatory mechanism would appear to occur, as a substantial increase in the amount of beta-1,3-glucan (2.34-fold) was detected in the cell wall of the mutant cells.
Garcerá
Ana
A
Department de Microbiología i Ecología, Facultat de Farmacia, Universitat de València, Avgda. Vicent Andrés Estellés s/n, 46100 Burjassot, València, Spain.
Castillo
Luis
L
Martínez
Ana I
AI
Elorza
María V
MV
Valentín
Eulogio
E
Sentandreu
Rafael
R
D000595:Amino Acid Sequence; D002176:Candida albicans / Q000737:chemistry* / Q000235:genetics* / Q000502:physiology; D002448:Cell Adhesion; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D011485:Protein Binding; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic; D047071:beta-Glucans / Q000032:analysis
D003470:Culture Media; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D047071:beta-Glucans; C033363:beta-1,3-glucan