Lecture 24 Flashcards
Compare M.tuberculosis to M.marinum
M.tuberculosis is a slow growing mycobacterium with no pigments, no environmental niches and its only host is humans, intracellularly, this intracellular growth is the only thing of these which is the same as with M.marinum. They have high homology at the protein level (85%) across 3000 related genes, changes for tuberculosis include rearrangements, inversions, deletions and acquisition via horizontal gene transfer (up to 80 regions). M.tuberculosis has a smaller genomic size with less genes but more IS elements, it has less PE and PPE genes and less metabolic flexibility.
What are the key points for horizontal gene transfer in M. tuberculosis?
When searching for horizontal gene transfer it is often important to look for regions of the genome which look like they could be mobile, also large changes in AT or GC frequency could signal that a DNA region has come from another organism. for M. tuberculosis 80 regions were predicted but other studies have predicted more, functions include membrane/lipid modification, metabolic functions, mobile elements, phage resistance.
What reduction compared to M.marinum led to M.tuberculosis having less metabolic flexibility?
M tuberculosis has half the number of transporters of M.marinum, this means it has less metabolic flexibility.
What is Mycobacterium Leprae and what are some key facts about its disease?
Mycobacterium Leprae causes leprosy, it is an unculturable slow grower (14 days to double), it is an obligate intracellular parasite which infects schwann cells of nerves and leads to loss of myelin and sensory loss and disfiguration. It’s mode of transmission is believed to be person to person contact but is not well understood and is not very contagious. Some protection is given by the BCG vaccine and treatment is typically multidrug therapy(6-12 months).
How does M.leprae compare to M.marinum?
M.leprae has half the genes of M.marinum and 1/4 of the genes from M.marinum have ecome pseudogenes another quarter of the genome people can’t tell what it is. At least 2000 genes have been lost, this is common in parasites and the genes/ regions might be in the process of being eliminated, however there are not many IS elements mediating the reduction, instead M.leprae lacks DNA proofreading activies which could account for mutations, there are also large scale genomic arrangements promoted by repeat regions.
What does M.leprae have in way of PE and PPE enes and what does this show?
M.leprae only has 9 PE and PPE genes and 30 pseudogenes, showing these are less required by M.leprae.
What can we use to determine antibiotic resistance?
M.leprae only has 9 PE and PPE genes and 30 pseudogenes, showing these are less required by M.leprae.
