Human Anatomy, Physiology, and Medicine. Anything human!
What do you mean body parts?
Racists? No, I am not racist. And....I did not take the blue pill or the red pill.
Wait.......U of M has a problem though. Oh yeah!
Best paid University head in the country too.
Last edited by Skytroll on Tue May 02, 2006 2:07 pm, edited 1 time in total.
Saliva of Insects> Pore forming........
It's hard to read somewhat, but worth it.
and this good one here too.....
Solution structure of the pore-forming protein of Entamoeba histolytica.
Amoebapore A is a 77-residue protein from the protozoan parasite and human pathogen Entamoeba histolytica. Amoebapores lyse both bacteria and eukaryotic cells by pore formation and play a pivotal role in the destruction of host tissues during amoebiasis, one of the most life-threatening parasitic diseases. Amoebapore A belongs to the superfamily of saposin-like proteins that are characterized by a conserved disulfide bond pattern and a fold consisting of five helices. Membrane-permeabilizing effector molecules of mammalian lymphocytes such as porcine NK-lysin and the human granulysin share these structural attributes. Several mechanisms have been proposed to explain how saposin-like proteins form membrane pores. All mechanisms indicate that the surface charge distribution of these proteins is the basis of their membrane binding capacity and pore formation. Here, we have solved the structure of amoebapore A by NMR spectroscopy. We demonstrate that the specific activation step of amoebapore A depends on a pH-dependent dimerization event and is modulated by a surface-exposed histidine residue. Thus, histidine-mediated dimerization is the molecular switch for pore formation and reveals a novel activation mechanism of pore-forming toxins.
This discussion has been controversial thus leading us to update our forum regulations so before continuing posting in this discussion please read the forum rules:
Please note that we will be deleting posts and warning or even banning members in accordance to those rules - in a harsher manner then previously.
Someone called CD 36, who is an engineer, posed this suggestion quite some time ago. He said:
'I realized there seems to be quite the connection between this and hair.......one guy said it seems to be growing around his hair or in his hair, people say its worse on the top of their heads (naturally where more hair is), and people report massive hair loss. Maybe its connected with your hair.......if this is completely stupid just let me know but i just wanted to throw this out there.......in an area thats affected and seems to be causing problems with hair is there any way you can remove the hair that wouldnt be to painfull to the affected area?'
I think that he may have something here. As you all are only too aware, this infection does seem to be interlinked with hair and hair follicles. Some of you have complained of keratin erosion and hair loss. Others have complained of having what would seem to be fibers that are mimicking human hair.
Dr Amin, the parasitologist, states that his patients, who have neurocutaneous syndrome, always feel much better once the strange fibers have been removed.
Is this a remedy that you would agree with?
Hi Tam tam,
You said, in your helpful resume of how this infection can lead to a condition like the neurogenic bladder, that you hoped to demonstrate some link between this, and the role of the surface epithelial cell.
Would you please elaborate a little on this?
All connects to tissue replacing property.
Adaptive protein and inherent neuro toxic properties known from cyano.
Consistent seems the presence of a trypanosome
Its part of a multi lineage differentiation.
Hence dicing cell that (random) recombine and produce(secretome)
Its the protein that will adapt and arrest.
What infects native cell is a yet to answer question.
Fibers are modules; translations of above mentioned base architecture.
Color relates to insect wing technology.
More dominant gene expression is present.
Arrest obstructs vital signal exchange.
Hi Tam tam,
Thank you very much.
Insofar as this stray target is concerned, do you think that the people in charge of the original experiment are aware of what seems to have happened, or might they believe that it must be someone else's carelessness? Or, could it be that they are totally unaware of everything?
This is long but, the reference is 68 pages, however they discuss protein secretory influence on infection and breaking through cell wall. This is what I have wondered, how this breaks into our cell walls. How is it inducted into the tissue?
By vectored phage, or insect? or airborne?
or is it the sensory mechanisms?
"1145 Regulation of solute accumulation in bacteria and its physiological significance
Department of Microbiology, University of Groningen, NL - firstname.lastname@example.orgBacterial solute transport systems can be subdivided in three categories on the basis of their energetics: (i) primary transport
systems use the free energy that is released upon the hydrolysis of ATP; (ii) secondary transport systems use the free energy
that is stored in the electrochemical gradients of protons, sodium ions or other solutes across the membrane; (iii) group
translocation systems chemically modify the substrate concomitant with translocation. The latter group constitutes the
bacterial phosphoenolpyruvate sugar:phosphotransferase systems (PEP-PTS).
The primary ATP-dependent solute uptake systems in bacteria all belong to the class of A TP- b inding c assette (ABC)
family and use a binding protein to capture the substrate and to deliver it to the translocator complex. For long it was thought
that the use of binding proteins was restricted to these systems, but recently it has been shown that some secondary transport
systems also employ such accessory proteins. In general, the energetics and kinetics of the different types of transport
mechanisms are known quite precisely from in vitro studies in membrane vesicles or proteoliposomes. Within the context of
the cell there can be regulatory mechanisms superimposed on the systems, which then determine the solute accumulation
levels as well as the actual rates of transport. This will lead to solute concentration gradients that are far from thermodynamic
equilibrium. The focus of this paper is on these regulatory mechanisms and their specific physiological functions in bacteria.
1400 Arsenic transport systems from Escherichia coli to humans
B.P. ROSEN, H. BHATTACHARJEE, M. GHOSH & R. MUKHOPADHYAY
Dept. Biochem. & Molec. Biol., Wayne State Univ., Sch. Med., Detroit, MI USAResistance to arsenicals and antimonials evolved at least three times. 1) The ars operon of Escherichia coli plasmid R773
encodes both the ArsC arsenate reductase that reduces As(V) to As(III), and the ArsAB pump that extrudes arsenite and
antimonite. The ArsA ATPase is the catalytic subunit of the pump. ArsA homologues are present in members of every
kingdom, including prokaryotes, archaea and eukaryotes. ArsA has homologous N-terminal (A1) and C-terminal (A2) halves,
indicating an evolutionary origin by gene duplication and fusion. ATP hydrolysis is allosterically activated by As(III) or
Sb(III), ensuring that the pump does not hydrolyze ATP without coupled anion translocation. The crystal structures and
mechanisms of ArsA and ArsC will be discussed. 2) In Saccharomyces cerevisiae the ACR gene cluster encodes an
independently-evolved arsenic resistance. Acr2p is an arsenate reductase, and Acr3p is a secondary carrier for arsenite
extrusion. 3) Finally, the S. cerevisiae Ycf1p, an ABC transport ATPase, pumps As(SG)3 and other metal-thiol complexes into
the vacuole, conferring resistance. Supported by US Public Health Service Grants GM55425 and GM52216
Do secretory pathways provide the induction of proteins that relate to our proteins?
"1445 Type II protein secretion: the main terminal branch of the general secretory pathway
Laboratoire d’IngŽniŽrie des Syst?mes MacromolŽculaires, CNRS-IBSM-UPR9027, 31 Chemin Joseph Aiguier, 13402
Marseille Cedex 20, France - Tel: + 33 4 91164127 / Fax: + 33 4 91712124 / Email: email@example.comBacteria have evolved several secretory pathways to release proteins into the extracellular medium. In gram-negative bacteria,
the exoproteins cross a cell envelope composed of two successive hydrophobic barriers, the cytoplasmic and outer
membranes. In some cases, the protein is translocated at once across the cell envelope, directly from the cytoplasm to the
extracellular medium. In other cases, secretion occurs via a two-step process, and outer membrane translocation involves an
extension of the signal peptide-dependent pathway for translocation across the cytoplasmic membrane. With respect to the socalled
G eneral E xport P athway (GEP), this route was designated as the G eneral S ecretory P athway (GSP) and is widely
conserved among gram-negative bacteria. The type II secretion mechanism or main terminal branch (MTB) of the GSP,
involves 12-14 different Gsp proteins, which is the general term used to describe those proteins of the type II secretory
apparatus. Surprisingly, the deduced amino acid sequences and initial characterisation of the proteins indicated that only two
of the fourteen are effectively located in the outer membrane. All but one of the other proteins seem to be anchored in the
cytoplasmic membrane, with the remaining protein peripherally associated with the cytoplasmic side of the inner membrane.
This particular cell envelope distribution of the Gsp proteins renders difficult the investigation of their roles in the molecular
mechanism of outer membrane translocation. Multiple aspects of the GSP mechanism, including machinery assembly,
exoprotein recognition, energy requirement and pore formation for driving through the outer membrane, will be discussed"..........
"1600 Secretion and injection of Yop proteins by the Type III machines of Yersinia enterocolitica
DEBORAH M. ANDERSON, LUISA W. CHENG, VINCENT T. LEE, SARKIS MAZMANIAN, KUMERAN RAMAMURTHI,
CHRISTINA TAM & OLAF SCHNEEWIND
University of California, Los Angeles, Dept of Microbiology and Immunology, Los Angeles, CA, USAYersinia enterocolitica export toxic proteins during animal infections via a type III secretion mechanism. Some type III
secretion substrates are injected into the cytoplasm of the eukaryotic host cells while others are secreted into the extra-cellular
environment, and still others remain associated with the bacteria in a manner that presumably aids in the injection of the
effector Yops. All three destinations remarkably require the same type III secretion machine. The signal for secretion cannot
be distinguished on the basis of amino acid sequence similarity of the substrates. We have shown that type III machines in
Yersinia can recognize atleast 2 independent signals for secretion. One signal has been found in all Yops analyzed to date and
is located in the first 15 codons. This signal tolerates drastic amino acid mutations and thus appears to be located in the
mRNA sequence of the secretion substrate. The translation and targeting of the substrate to the secretion loci can be coupled
by the mRNA signal. Some of the Yops harbor a second secretion signal that is located in their amino acid sequences and
requires the binding of secretion chaperones. Those Yops that contain this signal are all injected into the eukaryotic cell,
though, not all injected Yops have been found to bind a secretion chaperone. The recognition of secretion signals during
infection may require an ordered program of gene expression. We have begun to reveal the importance of post-transcriptional
regulation of Yop expression. LcrH and YopD bind type III substrate mRNA, likely causing the repression of translation. The
absence of this translational regulation leads to the massive secretion of all Yops during infection rather than their specific
targeting to extra-bacterial locations. Thus, there may be an ordered sequence of protein expression that is required to
facilitate the accurate targeting of Yops....
1645 Assembly of bacterial adhesins across the outer membrane via the chaperone-usher pathway
Washington University St Louis, USA
Abstract not submitted
0900 DNA uptake by transformable bacteria
SANFORD A. LACKS
Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USADiscovery of natural systems for DNA uptake by cells began about fifty years ago. A brief survey of mechanisms for DNA
uptake in bacterial cells during viral infection, conjugation, and transformation shows them to be quite distinct, although the
latter two processes have similarities, such as the conversion of donor DNA to single strands on entry into a recipient cell.
Detailed examination of transformation by free DNA in three different bacterial species shows that they all undergo a transient
phase of competence for DNA uptake. The mechanisms for inducing competence, however, are distinctly different in the three
species. Nevertheless, the sets of proteins that are ultimately induced share considerable homology, which indicates that the
structures and mechanisms for uptake are similar. There appears to be an extrusion through the cell membrane and cell wall of
a protein complex composed of type IV pilin-like structural proteins. Apparently bound to this complex are functional
proteins for binding double-stranded DNA, nicking one strand, degrading the other, forming a pore in the membrane, and
pulling one strand into the cell. All except the degradative nuclease are induced during competence. Although the essential
proteins for DNA uptake have been identified, the precise mechanisms of uptake are still conjectural."
SOURCE: http://www.sgm.ac.uk/meetings/pdfabstra ... 999abs.pdf
Who is online
Users browsing this forum: No registered users and 1 guest