TY - JOUR TI - A moonlighting function of a chitin polysaccharide monooxygenase, CWR-1, in Neurospora crassa allorecognition AU - Detomasi, Tyler C AU - Rico-Ramírez, Adriana M AU - Sayler, Richard I AU - Gonçalves, A Pedro AU - Marletta, Michael A AU - Glass, N Louise A2 - Rokas, Antonis A2 - Barkai, Naama A2 - Berrin, Jean-Guy A2 - Johansen, Katja Salomon VL - 11 PY - 2022 DA - 2022/08/30 SP - e80459 C1 - eLife 2022;11:e80459 DO - 10.7554/eLife.80459 UR - https://doi.org/10.7554/eLife.80459 AB - Organisms require the ability to differentiate themselves from organisms of different or even the same species. Allorecognition processes in filamentous fungi are essential to ensure identity of an interconnected syncytial colony to protect it from exploitation and disease. Neurospora crassa has three cell fusion checkpoints controlling formation of an interconnected mycelial network. The locus that controls the second checkpoint, which allows for cell wall dissolution and subsequent fusion between cells/hyphae, cwr (cell wall remodeling), encodes two linked genes, cwr-1 and cwr-2. Previously, it was shown that cwr-1 and cwr-2 show severe linkage disequilibrium with six different haplogroups present in N. crassa populations. Isolates from an identical cwr haplogroup show robust fusion, while somatic cell fusion between isolates of different haplogroups is significantly blocked in cell wall dissolution. The cwr-1 gene encodes a putative polysaccharide monooxygenase (PMO). Herein we confirm that CWR-1 is a C1-oxidizing chitin PMO. We show that the catalytic (PMO) domain of CWR-1 was sufficient for checkpoint function and cell fusion blockage; however, through analysis of active-site, histidine-brace mutants, the catalytic activity of CWR-1 was ruled out as a major factor for allorecognition. Swapping a portion of the PMO domain (V86 to T130) did not switch cwr haplogroup specificity, but rather cells containing this chimera exhibited a novel haplogroup specificity. Allorecognition to mediate cell fusion blockage is likely occurring through a protein–protein interaction between CWR-1 with CWR-2. These data highlight a moonlighting role in allorecognition of the CWR-1 PMO domain. KW - allorecognition KW - polysaccharide monooxygenase KW - somatic cell fusion KW - non-self-recognition KW - cell fusion checkpoint KW - chitin JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -