Pathogenic fungi: leading or led by ambient pH?

Abstract

SUMMARY Pathogenic fungi have successfully attacked a wide range of hosts, which has forced them into ambient-adaptation. pH is one of the major ambient traits affecting the activity of pathogenicity factors secreted by the pathogen, hence, a pH sensing-response system was developed to enable the pathogen to tailor its arsenal to best fit its host. The pacC palA, B, C, F, H and I apparatus was first identified in Aspergillus nidulans and later found in other fungi. Secreted pathogenicity factors, such as cell wall degrading enzymes, were recognized to be controlled by environmental pH and later shown to be regulated by the pH regulatory system, either directly or by harbouring the pacC consensus sequence. The ability of the pathogen to actively increase or decrease its surrounding pH allows it to select the specific virulence factor, out of its vast arsenal, to best fit a particular host.

Structural Basis for Inhibition of Aspergillus niger Xylanase by Triticum aestivum Xylanase Inhibitor-I

“…Therefore, this small cysteine-rich TAXI-I domain can be classified as knottin-like. Loop L NdHa is further connected to the end of ␤-strand Ng by a fourth disulfide bridge between Cys 39 and Cys 124 . The TAXI-I structure also presents a disulfide bond between the ␤-strands Cr and Cv (Cys 282 -Cys 327 ) of the C domain and one interdomain disulfide connection between Cys 167 and Cys 378 .…”

Receptor Kinases in Plant-Pathogen Interactions: More Than Pattern Recognition

“…A loss-of-function fer mutant exhibits increased resistance to F. oxysporum (Masachis et al, 2016). Of note, hemitrophic and biotrophic fungal pathogens are known to cause extracellular alkalinization in plants, an important feature of their life styles (Prusky et al, 2001;Prusky and Yakoby, 2003). F. oxysporum mutants lacking F-RALF are unable to induce extracellular alkalinization and are less virulent in plants (Masachis et al, 2016).…”

An aspartic proteinase gene family in the filamentous fungus Botrytis cinerea contains members with novel features

“…There are numerous examples of the modulation of expression of genes encoding secreted enzymes in plantpathogenic fungi (Rollins & Dickman, 1998;St Leger et al, 1998;Wubben et al, 2000;Yakoby et al, 2000). Regulation is often such that the genes are expressed only in a pH environment in which their products are effective (Prusky & Yakoby, 2003).…”