PMID- 17189316
OWN - NLM
STAT- MEDLINE
DCOM- 20070516
LR  - 20181113
IS  - 0006-3495 (Print)
IS  - 1542-0086 (Electronic)
IS  - 0006-3495 (Linking)
VI  - 92
IP  - 6
DP  - 2007 Mar 15
TI  - Protein-protein association in polymer solutions: from dilute to semidilute to 
      concentrated.
PG  - 2139-49
AB  - In a typical cell, proteins function in the crowded cytoplasmic environment where 
      30% of the space is occupied by macromolecules of varying size and nature. This 
      environment may be simulated in vitro using synthetic polymers. Here, we followed 
      the association and diffusion rates of TEM1-beta-lactamase (TEM) and the 
      beta-lactamase inhibitor protein (BLIP) in the presence of crowding agents of 
      varying molecular mass, from monomers (ethylene glycol, glycerol, or sucrose) to 
      polymeric agents such as different polyethylene glycols (PEGs, 0.2-8 kDa) and 
      Ficoll. An inverse linear relation was found between translational diffusion of 
      the proteins and viscosity in all solutions tested, in accordance with the 
      Stokes-Einstein (SE) relation. Conversely, no simple relation was found between 
      either rotational diffusion rates or association rates (k(on)) and viscosity. To 
      assess the translational diffusion-independent steps along the association 
      pathway, we introduced a new factor, alpha, which corrects the relative change in 
      k(on) by the relative change in solution viscosity, thus measuring the deviations 
      of the association rates from SE behavior. We found that these deviations were 
      related to the three regimes of polymer solutions: dilute, semidilute, and 
      concentrated. In the dilute regime PEGs interfere with TEM-BLIP association by 
      introducing a repulsive force due to solvophobic preferential hydration, which 
      results in slower association than predicted by the SE relation. Crossing over 
      from the dilute to the semidilute regime results in positive deviations from SE 
      behavior, i.e., relatively faster association rates. These can be attributed to 
      the depletion interaction, which results in an effective attraction between the 
      two proteins, winning over the repulsive force. In the concentrated regime, PEGs 
      again dramatically slow down the association between TEM and BLIP, an effect that 
      does not depend on the physical dimensions of PEGs, but rather on their mass 
      concentration. This is probably a manifestation of the monomer-like repulsive 
      depletion effect known to occur in concentrated polymer solutions. As a 
      transition from moderate to high crowding agent concentration can occur in the 
      cellular milieu, this behavior may modulate protein association in vivo, thereby 
      modulating biological function.
FAU - Kozer, Noga
AU  - Kozer N
AD  - Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, 
      Israel.
FAU - Kuttner, Yosef Yehuda
AU  - Kuttner YY
FAU - Haran, Gilad
AU  - Haran G
FAU - Schreiber, Gideon
AU  - Schreiber G
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20061222
PL  - United States
TA  - Biophys J
JT  - Biophysical journal
JID - 0370626
RN  - 0 (Bacterial Proteins)
RN  - 0 (Multiprotein Complexes)
RN  - 0 (Polymers)
RN  - 0 (Solutions)
RN  - 0 (beta-lactamase-inhibitor protein, Streptomyces)
RN  - EC 3.5.2.6 (beta-Lactamases)
RN  - EC 3.5.2.6 (beta-lactamase TEM-1)
SB  - IM
MH  - Bacterial Proteins/*chemistry
MH  - Binding Sites
MH  - Computer Simulation
MH  - *Models, Chemical
MH  - *Models, Molecular
MH  - Multiprotein Complexes/*chemistry
MH  - Polymers/*chemistry
MH  - Protein Binding
MH  - Protein Interaction Mapping/*methods
MH  - Solubility
MH  - Solutions
MH  - beta-Lactamases/*chemistry
PMC - PMC1861804
EDAT- 2006/12/26 09:00
MHDA- 2007/05/17 09:00
PMCR- 2008/03/15
CRDT- 2006/12/26 09:00
PHST- 2006/12/26 09:00 [pubmed]
PHST- 2007/05/17 09:00 [medline]
PHST- 2006/12/26 09:00 [entrez]
PHST- 2008/03/15 00:00 [pmc-release]
AID - S0006-3495(07)71018-4 [pii]
AID - 97717 [pii]
AID - 10.1529/biophysj.106.097717 [doi]
PST - ppublish
SO  - Biophys J. 2007 Mar 15;92(6):2139-49. doi: 10.1529/biophysj.106.097717. Epub 2006 
      Dec 22.