Structure and Composition of Eisosomes in Neurospora crassa
Diversely essential biochemical processes occur at the plasma membrane and require lateral separations. Eisosomes are protein containing microdomains at the plasma membrane in fungi and algae. They are spatially stable structures and are expected to have important function(s). However, the exact composition and the significant function(s) of eisosomes are still subjects of debate to date. This PhD thesis aims to improve the understanding about the composition, formation, and functions of eisosomes with the study in the model organism Neurospora crassa. In this thesis, studies on eisosomes in N. crassa are systematically described and discussed: (i) Using the immunogold transmission electron microscope (TEM) and yeast complementary approaches, the eisosomal fundamental component LSP-1 was identified in N. crassa and was used as the eisosomal marker protein. (ii) The red fluorescent protein (RFP) tagged LSP-1 was employed to recognize the localization characteristics of eisosomes in N. crassa. By confocal laser scanning microscopy and fluorescence profile analysis, the distribution of eisosomes were found to be different in different type of cells of N. crassa. There was polar and restriction distribution of eisosomes in the hyphae germinating from macroconidia. (iii) After the liquid chromatography-tandem mass spectrometry (LC-MS) analysis of the LSP-1 coupled protein fragments, the initial composition of eisosomes in N. crassa was recognized and the structure of eisosomes was predicted. According to the eisosomal protein analysis, the multiple functions of eisosomes in N. crassa were proposed in the PhD thesis. (iv) In addition, eisosomes have stable fluorescence patterns similar to actin patches, combining with the data mentioned above, the relationships between eisosomes and the cytoskeleton were closely examined. It was first been described that the disassembly of microtubules or F-actins influences the distribution of eisosomes in N. crassa. In conclusion, this PhD thesis systematically describes and discusses the composition and structure, functions, and the formation and regulation of eisosomes in the model fungus N. crassa for the first time. It bridges the studies of eisosomes in N. crassa and other fungi, and contributes to a better understanding about eisosomes.