Phospholipid Transfer Protein Activity in Rhodopseudomonas Sphaeroides
Tai, Shih-Peng
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/71175
Description
Title
Phospholipid Transfer Protein Activity in Rhodopseudomonas Sphaeroides
Author(s)
Tai, Shih-Peng
Issue Date
1985
Department of Study
Microbiology
Discipline
Microbiology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Microbiology
Abstract
A protein capable of transferring phospholipid between membranes has been purified from photosynthetic cells of Rhodopseudomonas sphaeroides. When compared to the crude cell lysate, this phospholipid transfer protein has been purified approximately 1,400-fold with a recovery of 12.5%. The active protein is a globular monomer having a molecular weight of 27,000 and an isoelectric point of 5.2. This protein can transfer all phospholipid species tested with the order of efficiency of transfer being phosphatidylglycerol > phosphatidylcholine > phosphatidylethanolamine. Based on the differences in binding to phenyl-sepharose and in isoelectric point, there apparently are at least two different phospholipid transfer proteins in the cell lysate.
Phospholipid transfer protein activity can be detected in the cell lysates of photosynthetically, as well as chemoheterotrophically, grown R. sphaeroides. Cells growing under different growth conditions have different amounts of the phospholipid transfer protein activity and this difference may merely reflect the difference in growth rate of the cells. Studies employing synchronous cultures show that the level of the phospholipid transfer activity is directly proportional to the cell number of the culture. The increase of specific activity of the phospholipid transfer activity is coincident with the increase in cell number and with the event of transferring phospholipid into the intracytoplasmic membrane during the cell cycle. It is possible that rapidly dividing cells may require an increased level of phospholipid transfer activity in order to satisfy their requirement for membrane synthesis.
The distribution of phospholipid transfer activity between soluble and membrane-associated forms is affected by the cellular growth conditions. Low light grown cells have the highest amount of intracytoplasmic membrane as well as the fraction of membrane-associated phospholipid transfer activity. The whole cell phospholipid transfer activity is further localized into periplasmic and cytoplasmic fractions.
The physiological role of the phospholipid transfer protein is suggested to be involved in intermembrane phospholipid translocation and in membrane lipid metabolism, lipid turnover or the modulation of the activities of membrane-associated proteins.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
