A signal peptide secretion screen in Fucus distichus embryos reveals expression of glucanase, EGF domain-containing, and LRR receptor kinase-like polypeptides during asymmetric cell growth.
Zygotes of the brown alga Fucus distichus (L.) Powell develop polarity prior to the first embryonic cell division and retain a pattern of asymmetric growth during early embryogenesis. In order to identify F. distichus polypeptides secreted during asymmetric cell growth, we used a functional assay in Saccharomyces cerevisiae to screen a cDNA library generated from asymmetrically growing Fucus embryos for sequences encoding polypeptides that function as signal peptides for secretion. We isolated and sequenced 222 plasmids containing Fucus cDNAs encoding signal peptide activity. The cDNA inserts from these plasmids were translated in silico into 244 potential polypeptide sequences, 169 of which are predicted to contain signal peptides. BlastP analysis of the Fucus sequences revealed similarity between many Fucus proteins and cell surface proteins that function in development in other eukaryotes, including epidermal growth factor (EGF)-like repeat-containing proteins, plant leucine-rich repeat (LRR)-receptor kinases, and algal beta-1, 3-exoglucanase. However, most of the isolated Fucus polypeptides lack similarity to known proteins. The isolation of cDNAs encoding secreted Fucus proteins provides an important step toward characterizing cell surface proteins important for asymmetric organization and growth in fucoid embryos.
Belanger
Kenneth D
KD
Department of Biology, University of North Carolina--Chapel Hill, Chapel Hill, NC 27759, USA. kbelanger@mail.colgate.edu
Wyman
Aaron J
AJ
Sudol
Michelle N
MN
Singla-Pareek
Sneh L
SL
Quatrano
Ralph S
RS
D000595:Amino Acid Sequence; D004815:Epidermal Growth Factor / Q000737:chemistry*; D044645:Fucus / Q000502:physiology*; D015723:Gene Library; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011494:Protein Kinases / Q000737:chemistry; D021382:Protein Sorting Signals / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014170:Transformation, Genetic
D021382:Protein Sorting Signals; D004815:Epidermal Growth Factor; D011494:Protein Kinases