A Patched-Like Protein PsPTL Is Not Essential for the Growth and Response to Various Stresses in Phytophthora sojae

Abstract

Patched (Ptc) and Patched-related (Ptr) proteins containing sterol-sensing domains (SSD) and Patched domains are highly conserved in eukaryotes for lipid transport and metabolism. Four proteins containing predicted SSD and Patched domains were simultaneously found by searching the Phytophthora sojae genome database, and one of them was identified as a Patched-like (PTL) protein. Here, we investigated the biological function of PsPTL. The expression level of PsPTL was higher during mycelial and sporulation stages, compared to zoospore (ZO), cyst, and germinated-cyst stages, without significant change during infection. However, deletion of PsPTL using CRISPR/Cas9 had no significant effect on the growth, development, or virulence of P. sojae. Further investigations showed that PsPTL is not essential for P. sojae to cope with external stresses such as temperature, pH, oxidative and osmotic pressure. In addition, this gene did not appear to play an essential role in P. sojae’s response to exogenous sterols. The transcript levels of the other three proteins containing predicted SSD and Patched domains were also not significantly upregulated in PsPTL deletion transformants. Our studies demonstrated that PsPTL is not an essential protein for P. sojae under the tested conditions, and more in-depth research is required for revealing the potential functions of PsPTL under special conditions or in other signaling pathways.

Sterol-Sensing Domain (SSD)-Containing Proteins in Sterol Auxotrophic Phytophthora capsici Mediate Sterol Signaling and Play a Role in Asexual Reproduction and Pathogenicity

“…Therefore, it was predicted that PcSCP1, PcSCP2, and PcSCP4 are NPC1 related proteins, while PcSCP3 is a Patched-like protein. This is in agreement with the findings from a previous study analyzing the phylogeny of SCPs from P. sojae ( 18 ). Transmembrane domain prediction indicated that these four PcSCPs contain 13, 13, 10, and 13 transmembrane domains, respectively ( Fig.…”

“…Knocking out of PcSCP3 individually or on the basis of double-gene knockout strain had no obvious impact on biological characteristics, indicating that this gene may not be essential for P. capsici . This is consistent with the results of another study, where the ortholog of PcSCP3 was individually knocked out in P. sojae ( 18 ). We also found some of the single-gene knockout transformants, when treated with sterol, produced fewer zoospores compared to the wild-type strain.…”

“…The SSD is a signature of many proteins that are important for sterol signal transduction pathways involved in sterol transport and sterol sensing in animals and yeasts ( 19 , 23 , 24 ). Interestingly, four genes encoding SSD-containing proteins (SCPs) were identified in different Phytophthora species ( 9 , 18 ). In addition to the SSD these SCPs also contain the Patched domain and three of them contain the NPC1_N domain.…”

“…For phylogenetic analysis, the protein sequences of SCPs from different eukaryotic lineages were retrieved from the NCBI database, including HMGCR, SCAP, NPC1, PTC, and DISP proteins from Homo sapiens , Bos taurus , Mus musculus , and Gallus gallus . In addition, four homologs of PcSCPs were identified from the genome data of P. sojae ( 18 ) and verified with the ORF Finder and RT-PCR. The phylogenetic tree was constructed with Mega 6.0 ( 47 ).…”

“…must possess intracellular sterol signaling networks, likely involving intracellular transport and homeostasis of sterols, and signal transduction mediated by sterols. Interestingly, four sterol-sensing domain (SSD)-containing proteins (SCPs) have been identified in Phytophthora capsici and Phytophthora sojae based on genome data analyses ( 9 , 18 ).…”