PMID- 28932813
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20191120
IS  - 2379-5042 (Print)
IS  - 2379-5042 (Electronic)
IS  - 2379-5042 (Linking)
VI  - 2
IP  - 5
DP  - 2017 Sep-Oct
TI  - 14-3-3 Regulates Actin Filament Formation in the Deep-Branching Eukaryote Giardia 
      lamblia.
LID - 10.1128/mSphere.00248-17 [doi]
LID - e00248-17
AB  - The phosphoserine/phosphothreonine-binding protein 14-3-3 is known to regulate 
      actin; this function has been previously attributed to sequestration of 
      phosphorylated cofilin. 14-3-3 was identified as an actin-associated protein in 
      the deep-branching eukaryote Giardia lamblia; however, Giardia lacks cofilin and 
      all other canonical actin-binding proteins (ABPs). Thus, the role of G. lamblia 
      14-3-3 (Gl-14-3-3) in actin regulation was unknown. Gl-14-3-3 depletion resulted 
      in an overall disruption of actin organization characterized by ectopically 
      distributed short actin filaments. Using phosphatase and kinase inhibitors, we 
      demonstrated that actin phosphorylation correlated with destabilization of the 
      actin network and increased complex formation with 14-3-3, while blocking actin 
      phosphorylation stabilized actin filaments and attenuated complex formation. 
      Giardia's sole Rho family GTPase, Gl-Rac, modulates Gl-14-3-3's association with 
      actin, providing the first connection between Gl-Rac and the actin cytoskeleton 
      in Giardia. Giardia actin (Gl-actin) contains two putative 14-3-3 binding motifs, 
      one of which (S330) is conserved in mammalian actin. Mutation of these sites 
      reduced, but did not completely disrupt, the association with 14-3-3. Native gels 
      and overlay assays indicate that intermediate proteins are required to support 
      complex formation between 14-3-3 and actin. Overall, our results support a role 
      for 14-3-3 as a regulator of actin; however, the presence of multiple 
      14-3-3-actin complexes suggests a more complex regulatory relationship than might 
      be expected for a minimalistic parasite. IMPORTANCEGiardia lacks canonical 
      actin-binding proteins. Gl-14-3-3 was identified as an actin interactor, but the 
      significance of this interaction was unknown. Loss of Gl-14-3-3 results in 
      ectopic short actin filaments, indicating that Gl-14-3-3 is an important 
      regulator of the actin cytoskeleton in Giardia. Drug studies indicate that 
      Gl-14-3-3 complex formation is in part phospho-regulated. We demonstrate that 
      complex formation is downstream of Giardia's sole Rho family GTPase, Gl-Rac. This 
      result provides the first mechanistic connection between Gl-Rac and Gl-actin in 
      Giardia. Native gels and overlay assays indicate intermediate proteins are 
      required to support the interaction between Gl-14-3-3 and Gl-actin, suggesting 
      that Gl-14-3-3 is regulating multiple Gl-actin complexes.
FAU - Krtkova, Jana
AU  - Krtkova J
AUID- ORCID: 0000-0002-9197-9730
AD  - Department of Biology, University of Washington, Seattle, Washington, USA.
AD  - Department of Experimental Plant Biology, Faculty of Science, Charles University, 
      Prague, Czech Republic.
FAU - Xu, Jennifer
AU  - Xu J
AD  - Department of Biology, University of Washington, Seattle, Washington, USA.
FAU - Lalle, Marco
AU  - Lalle M
AUID- ORCID: 0000-0001-5168-2150
AD  - Department of Infectious Diseases, Istituto Superiore di Sanita, Rome, Italy.
FAU - Steele-Ogus, Melissa
AU  - Steele-Ogus M
AD  - Department of Biology, University of Washington, Seattle, Washington, USA.
FAU - Alas, Germain C M
AU  - Alas GCM
AD  - Department of Biology, University of Washington, Seattle, Washington, USA.
FAU - Sept, David
AU  - Sept D
AUID- ORCID: 0000-0003-3719-2483
AD  - Department of Biomedical Engineering and Center for Computational Medicine and 
      Bioinformatics, University of Michigan, Ann Arbor, Michigan, USA.
FAU - Paredez, Alexander R
AU  - Paredez AR
AUID- ORCID: 0000-0002-9298-3264
AD  - Department of Biology, University of Washington, Seattle, Washington, USA.
LA  - eng
GR  - R01 AI110708/AI/NIAID NIH HHS/United States
PT  - Journal Article
DEP - 20170913
PL  - United States
TA  - mSphere
JT  - mSphere
JID - 101674533
PMC - PMC5597967
OTO - NOTNLM
OT  - 14-3-3
OT  - Rho GTPase
OT  - actin
OT  - evolutionary cell biology
EDAT- 2017/09/22 06:00
MHDA- 2017/09/22 06:01
PMCR- 2017/09/13
CRDT- 2017/09/22 06:00
PHST- 2017/05/26 00:00 [received]
PHST- 2017/08/21 00:00 [accepted]
PHST- 2017/09/22 06:00 [entrez]
PHST- 2017/09/22 06:00 [pubmed]
PHST- 2017/09/22 06:01 [medline]
PHST- 2017/09/13 00:00 [pmc-release]
AID - mSphere00248-17 [pii]
AID - 10.1128/mSphere.00248-17 [doi]
PST - epublish
SO  - mSphere. 2017 Sep 13;2(5):e00248-17. doi: 10.1128/mSphere.00248-17. eCollection 
      2017 Sep-Oct.