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The Metarhizium anisopliae Perilipin Homolog MPL1 Regulates Lipid…

- - - - perilipin-like proteins have also been selected to cope with different tasks as the absence of MPL1 produced unique phenotypes, including reduced appressorial turgor pressure and decreased virulence against an insect host
  - - - Include the N-terminals,b-strands and central three hydrophobic regions that targets and anchors Per A to LDs
      - Critical for TAG storage
      - Phosphorylation of perilipin by cAMPdependent
        protein kinase
        
        comformational change of peripilins
        
        initiates lypolysis by hormone -sensitive lipid
  - - - MPL1 operates in a perilipin-like manner
        
        localizing to lipid droplets and modulating the rate of hydrolysis
    - - perilipin-like proteins in the most
        diverse eukaryotes share an ancestral function
  - - - yeast has lost, or never acquired, the phosphorylation mechanism for removing perilipin-like proteins to access LDs.
  - - - cell compartmentalization is also required in rice blast fungus M. grisea to generate appressorial turgor
    - - a general phenomenon among pathogenic ascomycetes as Cap20 mutants of the plant pathogen C. gloeosporioides also have diminished virulence
- - - - Eukaryotic cells contain droplets of triglycerides encased in phospholipid membranes
      - Best studied
        
        Mammalian proteins of the perilipin family (PAT family)
        
        Perilipin
        
        By coating the droplets, perilipin forms a barrier that restricts the access of cytosolic lipases
        
        During food deprivation, perilipin is phosphorylated by protein kinase A
        
        Barrier function of perilipin is attenuated, lipolysis increases
        
        Adipocyte differentiation-related protein
        
        TIP47
        
        Has characteristic series of hydrophobic sequences (PAT domain) that facilitates their localization to the surface of lipid droplets
      - In perilipin-deficient mice
        
        Less fat, more muscle
        
        Higher metabolic rate
        
        Resistant to diet-induced & genetic obesity
      - In Drosophila lacking perilipin homolog, resulted with flies with less fat
      - Human perilipin variants are associated with obesity or leanness
      - Perilipin-free animals, hormone-sensitive lipase metabolizes fat as soon as it is made
    - - Inert storage vessels for energy-rich fat
      - Additional roles in maintaining membranes & moving components around cells
    - - Lipid diseases
      - Inflammation
      - Diabetes
      - Cardiovascular disease
      - Liver disease
    - - Metabolically active
      - Membranes encasing them have proteins with wide ranging biochemical activities
- - - - total number of LDs diminishes by 62% indicative of lipid degradation and the remaining LDs migrate into the germ tube apexes
    - - Aggregated
      - Albeit small
      - Clusters of LDs at the poles of Mpl1 conidia
      - Successful transportation of residual LDs to their hyphal tipsindicate that Mpl1 is not crucially involved in mediating the positioning of droplets in Metarhizium
        
        Contrast with Drosophila where perilipin regulates transportation of LDs
    - - Mpl1 appressoria frequently contained no LDs at all
  - - - consensus cAMP-dependent protein kinase phosphorylation site at position 96 in a region conserved with Per A
    - - Each pezizomycotinal fungus has only a single perilipinlike gene
  - - - expressing it with Gal1-inducible promoter in yeast S. cerevisiae
      - system lacks endogenous perilipin-like proteins
  - - - This suggests that lipolysis of LDs and consequent production of solutes produce turgor in the wild type.
    - - The mutant failed to achieve 50% mortality before the insects pupated
        
        However, when the cuticle was by passed by injecting spores directly into the hemocoele,the speed of kill by the WT and the mutant were not significantly different.
        
        The results indicate that the lack of Mpl1 affects fungal virulence by reducing mechanical penetration of the host cuticle