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Microbiology and Immunology 4100A Lecture Notes - Lecture 17: Hemolysis, Acyltransferase, Endocytosis

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mauveyak622
22 Dec 2019
School
Western University
Department
Microbiology and Immunology
Course
Microbiology and Immunology 4100A
Professor
Martin Mc Gavin

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Document Summary

B hemolysis completelysisofrbcs clearingaroundcolonies spyogenes x hemolysis partiallysisofroses producesagreenishdiscolouration ofthebloodagararoundthecoloniesdue tothehydrogenperoxidemadebythebacteriawhichinteractswithhemoglobintomakebiliverdingreen nohemolysisofrbcs: r hemolysis. Includestokcor cyae in bpertussis outermembraneprotein thesetoxinsrequireposttranslationalmodification fattyacidacylationofthestructuralrtxaproteinbyrtxc repeatthertxhallmark region. Glyandasp richnonapeptidec9aminoacidssequencerepeatedintandemneartheproteinc terminus repeatsanewfor caa binding ca requiredforcytolyticactivitybutnotformembranebinding. Ecoli x hemolysin hiya synthesisandsecretion atoxin signalpeptideisnotcleared getsrecognized synthesisofproteina willthengetmodifiedwithafattyacidbyan acylcarrierprotein acylacp cproteinremovesthefattyacidandputsit onthetoxin acyltransferase: banddproteinsmakeupthesecretionportal poweredbyatpase. Membraneinsertion thesecretedtoxiniswatersoluble willundergoreversibleabsorptiontothemembrane willassociatewiththe membranebutnotpermenantly uponcartbindingtheproteinundergoesamassivestructuralchangethat causesexposureandinsertionofthefattyacidintothemembrane causesirreversibleinteractionwiththehostmembrane. Endosomewillacidifycausingthetoxinto dissociate toxinwillcauseholestobeproducedintheresides entersintothe cytoplasm willinteractwiththemitochondriacausingdamage mi i w e ho ng ge releaseofcytochromecfromthemitochondria causescaspase aactivationleadingtoapoptosis theantibioticbafilomycininhibitsacidificationoftheendosomeinhibitingapoptosis. Bordertellapertussisproducesa calmodulin dependentadenylatecyclase cyanisoneofmajortoxinsproducedbybpercussis cyaatoxinrequirestheactivityofaccessoryproteinsforpost translational modificationandsecretiontype1secretioni componentsarehomologoustothe ecolihemolysinsystem. Associateswiththemembrane allowingca binding causesrearrangementoftheproteinflippingthewterminusintothecell interactionoftheadenylatecyclasedomainwithendogenouscalmodulin causesextremelyrapidcatalysisofatp camp incampinhibitstheoxidateburstandcomplement mediated opsonophagocytickillingofbacteria enablesthepathogentocolonizehostairways. Listeriainvadestheintestinalepithelium wantstoescapethemembranebound vesicle uo degradesthemembrane virulencefactoractapolymerizesactinatthetipanddepolymerizesattheend causeslisteriatobepushedaroundthecell if it isfastenough itcanenterintotheneighbouringcells willthenbeboundbyadoublemembrane. Ifsomeofthetoxingetstotheextracellularmembrane itwillgetphosphorylatedatthepestsequence degradationsignal the willgetboundbythea2complexcausingavesicletobeformedfromtheoutermembraneandbendoffintothe cytosol vesiclewillgetengulfedintoanautophagosome ormultivesicularbodyandgetdegraded preventsthedeathofthecell. B i g i madebygrampositivebacteria toxinsaresecretedassolubleproteins primarysequenceis hydrophilic onlyhasonehydrophobicspanningdomain largedegreeofb structure transmembrane oligomericb barrelwithhydrophobicresiduesfacinglipidsandhydrophilicresiduesfacingtheinteriorchannel oligomerizesin 7 or8 forming aporethatallowssmallionstoleakout. Eachmonomercontributesasmallhydrophobiastructurethatwhencombinedcreateastableinteractionwiththeinterior ofthebilayer inthesolubleformthesehydrophobicdomainsaremaskedbyfolding formsa heptamer pore outsideofthebarrelishydrophobicwhilethechannellumenishydrophilic cellsdieduetolossofatpandcriticalions. Oligomerizingdomainbindsabamio allowingthehairpintoinsertintothemembrane knockoutof adamoresultsinresistanceto x toxin a toxincausesnecrotizingpneumoniaandskinpathologyduetointeractionwithadamlo. Adamohasactivitywith ecadherin x toxinbirdstoandactivatesadamocausing it tobreakthetightjunctionsmadebye cadherin intightjunctions.

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Related Questions

Immunology worksheet help?

1. In people infected with human cytomegalovirus, class I MHC andb2-microglobulin are produced, but very little mature class I MHCis found at the cell surface. Inhibition of which of the followingmolecules by human cytomegalovirus may account for thisphenomenon?
A. TAP
B. Ii
C. TCR
D. CLIP
E. RAG
2. Your chances of having the same MHC haplotype as your siblingare:
A. 1:2.
B. 1:4.
C. 1:16.
D. 1:8.
E. 1:1.
3. Which of the following is the BEST example of self-MHCrestriction of T cells?
A. A T-cell clone is deleted when it binds too tightly to selfMHC.
B. A T-cell clone responds more vigorously to a self-peptide thana foreign peptide.
C. A T-cell clone recognizes foreign MHC.
D. A T-cell clone only recognizes foreign peptides when presentedby self MHC.
E. All of the above
4. MHC molecules:
A. are conserved between individuals.
B. bind repeating patterns found on pathogens.
C. are recognized by T cells.
D. are membrane-bound molecules found exclusively on T cells.
E. are secreted by T cells and bind and neutralize antigen in theserum.
5. Tasmanian devils are a largely inbred population with littlediversity in the MHC. Which of the following would be a likelyoutcome of this?
A. They would compensate for low diversity in the MHC with highdiversity in the TCR.
B. They would compensate for low diversity in the MHC with highdiversity in the BCR.
C. They would rely only on innate immune responses.
D. They would be at higher risk of infection.
E. All of the above
6. How many different MHC classical class I proteins does eachnucleated cell in a human heterozygous at the MHC locusexpress?
A. Six
B. Two
C. Three
D. One
E. None. Only APC express class I.
7. MHC polymorphisms tend to cluster:
A. in the peptide-binding groove.
B. in the transmembrane domain.
C. in the coreceptor contact residues.
D. in the framework region.
E. All of the above
8. A mutation that renders the MHC class II molecule DMnonfunctional would likely lead to:
A. cells with no class II MHC.
B. a deficiency in CD8+ T cells.
C. cells with class II MHC only bound with CLIP.
D. cells with class II MHC bound with a variety ofself-antigens.
E. cells with no DO.
9. The human MHC locus is one of the most polymorphic regions ofthe genome. What does this mean?
A. This region is regulated by many different mechanisms.
B. Sequence variability is low in this region.
C. There are many introns in this region.
D. There are many different alleles of these genes.
E. It has the most different genes.
10. Which of the following is an example ofcross-presentation?
A. An exogenous peptide being presented on MHC class II
B. A B-cell antigen being presented to a T cell
C. An endogenous peptide being presented on MHC class I
D. An endogenous peptide being presented on MHC class II
E. An exogenous peptide being presented on MHC class I

Hibernating animals and human infants contain brown fat deposits, so-called because of the presence of large numbers of mitochondria, the site of electron transport and oxidative phosphorylation. In brown fat, given the appropriate stimulus, oxidative phosphorylation and electron transport can be uncoupled, causing energy to be dissipated as heat. The protein responsible for the uncoupling is a brown fat inner mitochondrial membrane protein previously named UCP (for uncoupling protein), but now referred to as UCP1, since a second uncoupling protein has since been discovered. Previous experiments have shown that UCP1 protects against cold and is involved in regulation of energy expenditure. The ability of UCP1 to stimulate the consumption of calories solely for the production of heat led some investigators to postulate that UCP1 was involved in regulating body weight. Scientists have always wondered why some people seem to be able to ingest a large number of calories without gaining weight, whereas others eat moderately but are obese. If the UCP1 of brown fat were involved, scientists postulated that obese people would be efficient “burners”, whereas humans of moderate weight might burn calories inefficiently, releasing a greater proportion of energy as heat. But the role of UCP1 in humans has always been debated since infants contain a large amount of brown fat but mature adults do not. In order to examine the biochemical role of UCP1 more fully, the investigators in this case worked with mice referred to as knockouts. Knockout mice have been genetically engineered such that the gene coding for a particular protein is missing. By examining the characteristics of knockout mice, the biochemical and physiological roles of a particular protein can be ascertained. The investigators produced UCP1-knockout mice that are missing the gene for the UCP1 protein. They carried out experiments using these mice that are described below, studies that led to the discovery of a second uncoupling protein referred to as UCP2. The UCP2 protein may play a more significant role in obesity, since UCP2 is found in abundant amounts in white fat. References: Enerbäck, S., Jacobsson, A., Simpson, E. M., Guerra, C., Yamashita, H., Harper, M.-E., and Kozack, L.P. (1997) Nature 387, pp. 90-94. Fleury, C., Neverova, M., Collins, S., Raimbault, S., Champigny, O., Levi-Meyrueis, C., Bouillard, F., Seldin, M. F., Surwit, R. S., Ricquier, D., and Warden, C. H. (1997) Nature Genetics, 15, pp. 269-272. Lowell, B. B., S-Susulic, V., Hamann, A., Lawitts, J. A., Himms-Hagen, J., Boyer, B. B., Kozak, L. P., and Flier, J. S. (1993) Nature 366, pp. 740-742. Hirsch, J. (1997) Nature 387, pp. 27-28. 16.

Why is heat produced when UCP1 protein uncouples oxidative phosphorylation from electron transport?