Microbiology 微生物学 Spring-Summer

Transcription

1

2 Microbiology 微生物学 2016 Spring-Summer

3 Relevant Information and Resources Course slides can be found at 教学工作 Course-related questions will be answered through s. Textbook: Brock Biology of Microorganisms (13 th )

4 Cytoplasmic Membrane

5 Cytoplasmic Membrane Hydrophilic region Hydrophobic region Fatty acids Hydrophilic region Glycerol Phosphate General chemical structure of phospholipid Glycerophosphates Fatty acids TEM of a membrane from Halorhodospira halochloris H-bonds & hydrophobic interactions Mg 2+, Ca 2+, + phospholipids ionic bonds

6 Cytoplasmic Membrane 6 8 nm Phospholipids Out Hydrophilic groups Hydrophobic groups Integral membrane proteins In Phospholipid molecule Sterols in eukaryotes Integral One-end inserted Peripheral Unevenly distributed functionally clustered Rigidity agents Hopanoids in bacteria, missing in Archaea

7 Cytoplasmic Membrane General structure of lipids in Archaea 6 8 nm Phospholipids Out In Hydrophilic groups Hydrophobic groups Integral membrane proteins Phospholipid molecule a. Eukaryote and Bacteria; b. Archaea; Ester or ether? Fatty acids or repeated isoprene c. Isoprene

8 Cytoplasmic Membrane Major lipids of Archaea and the structure of archaeal cytoplasmic membranes Ether linkage Phytanyl Isoprene unit Glycerol diether CH 3 groups Isoprene unit Biphytanyl Diglycerol tetraethers Extremely resistant to heat

9 Cytoplasmic Membrane Major lipids of Archaea and the structure of archaeal cytoplasmic membranes Crenarchaeol Out Out Glycerophosphates Phytanyl Membrane protein Biphytanyl In In Lipid bilayer Lipid monolayer

10 Cytoplasmic Membrane

11 Cytoplasmic Membrane - Function 1. Permeability Barrier Prevents leakage and functions as a gateway for transport of nutrients into and out of the cell 2. Protein Anchor Site of many proteins involved in transport, bioenergetics, and chemotaxis 3. Energy Conservation Site of generation and use of the proton motive force

12 Cytoplasmic Membrane Even for water, specific transport proteins (aquaporins) are needed in certain cases.

13 Rate of solute entry Transport and transport systems Transporters versus diffusion Transporter saturated with substrate Transport Simple diffusion Characteristics of Transport Proteins: 1. Saturation effect; 2. High specificity; 3. Tightly regulated External concentration of solute

14 Transport and transport systems Simple transport: Driven by the energy in the proton motive force Out In Phosphoanhydride Phosphate ester Ribose Transported substance Group translocation: Chemical modification of the transported substance driven by phosphoenolpyruvate 1 ABC transporter: Periplasmic binding proteins are involved and energy comes from ATP 2 3 Phosphates Adenosine TriPhosphate (ATP) Adenine The three classes of membrane transport systems all require energy in some form, usually proton motive force or ATP

15 Transport and transport systems Out In Uniporter Antiporter Symporter Structure of membrane-spanning transporters and types of transport events

16 Simple transport Lac permease (a symporter) Sodium proton antiporter Phosphate symporter Potassium uniporter Function of the Lac permease symporter of Escherichia coli and several other wellcharacterized simple transporters Sulfate symporter Out In

17 Group translocation In Out Non-specific components Enz I HPr Specific components Enz II a Enz II b Enz II C Cytoplasmic membrane Pyruvate Direction of P transfer Glucose 6 P Glucose Direction of glucose transport Mechanism of the phosphotransferase system of Escherichia coli Phosphoenolpyruvate (PEP) Pyruvate

18 ABC system ABC: ATP-binding cassette Peptidoglycan Attached to the membrane in Grampositive Periplasm Out In Periplasmic binding protein Transported substance Membranespanning transporter ATPhydrolyzing protein Mechanism of an ABC transporter

19 Protein Secretion System

20 Protein Secretion System-Sec

21 Protein Secretion System-Sec

22 Cell Wall

23 Cell Wall O-polysaccharide Core polysaccharide Lipid A Protein Out Cell wall Outer membrane Porin Lipopolysaccharide (LPS) 8 nm Periplasm Cytoplasmic membrane Peptidoglycan Phospholipid Lipoprotein In

24 Cell Wall Gram-positive Peptidoglycan Gram-negative Outer membrane Cytoplasmic membrane Protein Protein Peptidoglycan Cytoplasmic membrane Cytoplasmic membrane Peptidoglycan Outer membrane

25 Cell Wall Gram Negative

26 Cell Wall Gram Positive

27 Cell Wall Escherichia coli Bacillus subtilis

28 Cell Wall - Peptidoglycan -- Missing in some prokaryotes, such as Mycoplasmas, and thermoplasma (archaea)

29 Cell Wall - Peptidoglycan N-Acetylglucosamine (G) N-Acetylmuramic acid (M) (1,4) (1,4) (1,4) N-Acetyl group Peptide cross-links Lysozymesensitive bond L-Alanine D-Glutamic acid Meso-diaminopimelic acid D-Alanine Gram negative Structure of the repeating unit in peptidoglycan

30 Cell Wall - Peptidoglycan Peptidoglycan in Escherichia coli and Staphylococcus

31 Cell Wall - Peptidoglycan

32 Cell Wall - Peptidoglycan N-Acetylglucosamine (G) N-Acetylmuramic acid (M) (1,4) (1,4) (1,4) N-Acetyl group Gram Positive Peptide cross-links Lysozymesensitive bond L-Alanine D-Glutamic acid Meso-diaminopimelic acid D-Alanine Structure of the repeating unit in peptidoglycan Diaminopimelic acid Lysine Cross-linking amino acids in peptidoglycan

33 Cell Wall - Peptidoglycan Common to have teichoic acids embedded in the call wall (lipoteichoic acids, with covalently bound membrane lipids)

34 Cell Wall - Peptidoglycan Target of some antibiotics, such as penicillin - biosynthesis, and lysozyme glycosidic bond

35 Lysozyme and Protoplasts Wall Membrane Lysozyme digests wall H 2 O enters Lysis H 2 O enters H 2 O enters Low solute solution Lysozyme digests wall Protoplasts and their formation: Lysozyme breaks the -1, 4, glycosidic bonds in peptidoglycan Protoplast Isotonic solute solution

36 Cell Wall the Outer Membrane -LPS replaces most of phospholipids in outer half of outer membrane - Endotoxin: the toxic component of LPS (Lipid A)

37 Cell Wall the Outer Membrane O-specific polysaccharide Core polysaccharide Lipid A n

38 The Outer Membrane O polysaccharide Core polysaccharide Lipid A Protein Out Lipopolysaccharide (LPS) Cell wall Outer membrane 8 nm Porin Periplasm Peptidoglycan Phospholipid Cytoplasmic membrane In Lipoprotein -Porins : channels for movement of hydrophilic lowmolecular weight substance - Abundant

39 The Periplasm - 15 nm wide - Contents have gel-like consistency - Houses many proteins

40 Cell Walls of Archaea Lysozyme-insensitive (1,3) N-Acetyl group N-Acetylglucosamine (G) N-Acetylmuramic acid (M) (1,4) (1,4) (1,4) N-Acetylglucosamine N-Acetyltalosaminuronic acid N-Acetyl group Peptide cross-links Peptide cross-links Lysozymesensitive bond L-Alanine D-Glutamic acid Pseudomurein - Typically no outer membrane - Pseudomurein (T vs. M; L-amino acids only) - Cell walls of some Archaea lack pseudomurein Meso-diaminopimelic acid D-Alanine

41 Part 3 Part 2 Part 1 Cell Walls of Archaea UA: uronic acid Glu: Glucose Gal: Galactose Gly: Glycine GluNac: N- acetylglucosamine GlaNac: N- acetylgalactosamine GulNUA: N- acetylgulosaminuron ic acid Polysaccharide cell walls of Archaea Man: Mantose

42 Cell Walls of Archaea The outermost layer Possible function: Protection layer from osmotic lysis; Selective sieve Protein anchor S-layer found in most Archaea and some Bacteria

43 Cell Walls of Archaea Methanomicrobia bacterium Aquaspirillum serpens

44 Other Cell Surface Structure and Inclusions

45 Other Cell Surface Structure and Inclusions

46 Other Cell Surface Structures Bacterial capsules and Slime layers (a) Acinetobactor by negative staining cells with India ink. (phase contrast) Cell Capsule (b) Rhodobacter capsulatus (TEM) (c) Rhizobium trifolii stained with ruthenium red. (TEM)

47 Other Cell Surface Structure

48 Other Cell Surface Structures Flagella Fimbriae Fimbriae (Salmonella) -Filamentous protein structures -Enable organisms to stick to surfaces or form pellicles

49 Other Cell Surface Structures Pili (Escherichia coli) Viruscovered pilus

50 Other Cell Surface Structures Type IV Pili & Twitching

51 Cell -carbon Inclusions Poly- hydroxylbutyrate (PHB), a common PHA, Rhodovibrio sodomensis Stained by Nile red Polyhydroxyalkanoate Also Glycogen, a polymer of glucose

52 Cell Inclusions Polyphosphate (a) Polyphosphate granules in Heliobacterium modesticaldum (b) Sulfur globules. Isochromatium buderi (in the periplasm) Sulfur

53 Cell Inclusions Magnetotactic bacteria and magnetosomes a. Coccoid magnetotactic bacteria b. Magnetosomes from Magnetaspirillum magnetotacticum c. Magnetosomes from a magnetic coccus

54 Cell Inclusions Cyanobacteria and Gas vesicles

55 Cell Inclusions Ribs Gas vesicle proteins GvpA GvpC

56 Endospores Bacillus & Clostridium The bacterial endospores

57 Endospores

58 Germination Sporulation and Endospores Vegetative cell Sporulating cell Developing spore Mature spore The life cycle of an endospore-forming bacterium

59 Endospores a. Endospore b. Refractility is being lost c. & d. The new vegetative cell is emerging. Endospore germination in Bacillus

60 Endospores Exosporium Spore coat Core wall Cortex DNA Structure of the bacterial endospore a. TEM b. Fluorescent

61 Endospores Carboxylic acid groups (a) Dipicolinic acid (DPA) (b) Ca 2+ crosslinks DPA

62 Endospores Sporulation in Bacillus subtilis: A, B, C, D, Wild-type; E, F, G, H, pyruvate dehydrogenase E1 deletion strains; I, J, K, L, E2 deletion strains Stained by FM4-64 (Red) and/or MTG (Green). DAPI was used to stain chromosomes

63 Sporulation and Endospores Coat Free endospore Maturation, cell lysis Spore coat, Ca 2 uptake, SASPs, dipicolinic acid Growth Germination Stage VI, VII Stage V Cortex Vegetative cycle Cell division Asymmetric cell division; commitment to sporulation, Stage I Sporulation stages Cell wall Cytoplasmic membrane Cortex formation Stage IV Prespore Septum Engulfment Mother cell Stage II Stage III

64 Spore Companioned Crystal Parasporal Endotoxins of B. thuringiensis

65 Spore Companioned Crystal

66 Endospores B. anthracis and Anthrax