scholarly journals Photocontrol of GTPase Cycle and Multimerization of the Small G-Protein H-Ras using Photochromic Azobenzene Derivatives

2021 ◽  
Vol 18 (4) ◽  
pp. 661-672
Author(s):  
Rufiat Nahar ◽  
Alam MD Noor A ◽  
Islam MD Alrazi ◽  
Shinsaku Maruta
Keyword(s):  
G Protein ◽  
Hypervariable Region ◽  
Cysteine Residues ◽  
Nucleotide Exchange ◽  
Ras Gtpase ◽  
Small G Protein ◽  
Sh Group ◽  
Cellular Signal ◽  
Gtpase Cycle ◽  
Azobenzene Derivatives

Ras is a small G protein known as a central regulator of cellular signal transduction that induces processes, such as cell division, transcription. The hypervariable region (HVR) is one of the functional parts of this G protein, which induces multimerization and interaction between Ras and the plasma membrane. We introduced two highly different in polarity photochromic SH group-reactive azobenzene derivatives, N-4-phenyl-azophenyl maleimide (PAM) and 4-chloroacetoamido-4-sulfo-azobenzene (CASAB), into three cysteine residues in HVR to control Ras GTPase using light. PAM stoichiometrically reacted with the SH group of cysteine residues and induced multimerization. The mutants modified with PAM exhibited reversible changes in GTPase activity accelerated by the guanine nucleotide exchange factor and GTPase activating protein and multimerization accompanied by cis- and trans-photoisomerization upon ultraviolet and visible light irradiation. CASAB was incorporated into two of the three cysteine residues in HVR but did not induce multimerization. The H-Ras GTPase modified with CASAB was photo controlled more effectively than PAM-H-Ras. In this study, we revealed that the incorporation of azobenzene derivatives into the functional site of HVR enables photo reversible control of Ras function. Our findings may contribute to the development of a method to control functional biomolecules with physiologically important roles.

scholarly journals Structure of small G proteins and their regulators.

2001 ◽  
Vol 48 (4) ◽  
pp. 829-850 ◽  
Author(s):  
M Paduch ◽  
F Jeleń ◽  
J Otlewski
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Protein Interactions ◽  
Sequence Similarity ◽  
Nucleotide Exchange ◽  
Microtubule Organization ◽  
Cellular Processes ◽  
Guanine Nucleotide Exchange ◽  
Small G Protein ◽  
Small G Proteins

In recent years small G proteins have become an intensively studied group of regulatory GTP hydrolases involved in cell signaling. More than 100 small G proteins have been identified in eucaryotes from protozoan to human. The small G protein superfamily includes Ras, Rho Rab, Rac, Sarl/Arf and Ran homologs, which take part in numerous and diverse cellular processes, such as gene expression, cytoskeleton reorganization, microtubule organization, and vesicular and nuclear transport. These proteins share a common structural core, described as the G domain, and significant sequence similarity. In this paper we review the available data on G domain structure, together with a detailed analysis of the mechanism of action. We also present small G protein regulators: GTPase activating proteins that bind to a catalytic G domain and increase its low intrinsic hydrolase activity, GTPase dissociation inhibitors that stabilize the GDP-bound, inactive state of G proteins, and guanine nucleotide exchange factors that accelerate nucleotide exchange in response to cellular signals. Additionally, in this paper we describe some aspects of small G protein interactions with down-stream effectors.

scholarly journals ECT2 associated to PRICKLE1 are poor-prognosis markers in triple-negative breast cancer

2018 ◽  
Author(s):  
Avais M. Daulat ◽  
Pascal Finetti ◽  
Diego Revinski ◽  
Mônica Silveira Wagner ◽  
Luc Camoin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Migration ◽  
G Protein ◽  
Poor Prognosis ◽  
Triple Negative ◽  
Molecular Signature ◽  
Breast Cancers ◽  
Nucleotide Exchange ◽  
Small G Protein ◽  
Proteomic Approach

AbstractBackgroundTriple-negative breast cancers are poor-prognosis tumors characterized by absence of molecular signature and are chemotherapy is still the only systemic treatment. Currently, research focus to identify biomarkers that may be usable for prognosis and/or for treatment, notably among the proteins involved in cell migration and metastatic capacity.MethodsWe used proteomic approach to identify protein complexes associated to PRICKLE1 and the mRNA expression level of the corresponding genes in a retrospective series of 8,982 clinically annotated patients with invasive primary breast cancer were assessed. Then, we characterize molecularly the interaction between PRICKLE1 and the guanine nucleotide exchange factor ECT2. Finally, experiments in Xenopus have been carrying out to determine their evolutionary conserved interaction.ResultsWe have identified a network of proteins interacting with the prometastatic scaffold protein PRICKLE1 that includes several small G-protein regulators involved in cell migration and metastasis. Combined analysis expression of PRICKLE1 and small G-protein regulators expression has a strong prognostic value in TNBC. We show that PRICKLE1 controls the activity of ECT2 on RAC1 signaling, a pathway required for cancer cell dissemination.ConclusionsThis work supports the idea that promigratory proteins, which are overexpressed in cancerous epithelium, are suitable pharmaceutical targets.

scholarly journals The small G protein Arl1 directs the trans-Golgi–specific targeting of the Arf1 exchange factors BIG1 and BIG2

2012 ◽  
Vol 196 (3) ◽  
pp. 327-335 ◽  
Author(s):  
Chantal Christis ◽  
Sean Munro
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Mammalian Cells ◽  
Affinity Purification ◽  
Nucleotide Exchange ◽  
Purification Method ◽  
Guanine Nucleotide Exchange ◽  
Small G Protein ◽  
Nucleotide Exchange Factor ◽  
Small G Proteins

The small G protein Arf1 regulates Golgi traffic and is activated by two related types of guanine nucleotide exchange factor (GEF). GBF1 acts at the cis-Golgi, whereas BIG1 and its close paralog BIG2 act at the trans-Golgi. Peripheral membrane proteins such as these GEFs are often recruited to membranes by small G proteins, but the basis for specific recruitment of Arf GEFs, and hence Arfs, to Golgi membranes is not understood. In this paper, we report a liposome-based affinity purification method to identify effectors for small G proteins of the Arf family. We validate this with the Drosophila melanogaster Arf1 orthologue (Arf79F) and the related class II Arf (Arf102F), which showed a similar pattern of effector binding. Applying the method to the Arf-like G protein Arl1, we found that it binds directly to Sec71, the Drosophila ortholog of BIG1 and BIG2, via an N-terminal region. We show that in mammalian cells, Arl1 is necessary for Golgi recruitment of BIG1 and BIG2 but not GBF1. Thus, Arl1 acts to direct a trans-Golgi–specific Arf1 GEF, and hence active Arf1, to the trans side of the Golgi.

Role of Magnesium in Nucleotide Exchange on the Small G Protein Rac Investigated Using Novel Fluorescent Guanine Nucleotide Analogues†

Biochemistry ◽  
2002 ◽  
Vol 41 (11) ◽  
pp. 3828-3835 ◽  
Author(s):  
Adam Shutes ◽  
Robert A. Phillips ◽  
John E. T. Corrie ◽  
Martin R. Webb
Keyword(s):  
G Protein ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Nucleotide Analogues ◽  
Small G Protein

The small GTPases Ras and Rheb studied by multidimensional NMR spectroscopy: structure and function

2017 ◽  
Vol 398 (5-6) ◽  
pp. 577-588 ◽  
Author(s):  
Miriam Schöpel ◽  
Veena Nambiar Potheraveedu ◽  
Thuraya Al-Harthy ◽  
Raid Abdel-Jalil ◽  
Rolf Heumann ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Point Mutations ◽  
Hypervariable Region ◽  
Small Gtpases ◽  
Multidimensional Nmr ◽  
Nucleotide Exchange ◽  
Nmr Studies ◽  
High Sequence Similarity ◽  
And Function ◽  
Gtpase Cycle

Abstract Ras GTPases are key players in cellular signalling because they act as binary switches. These states manifest through toggling between an active (GTP-loaded) and an inactive (GDP-loaded) form. The hydrolysis and replenishing of GTP is controlled by two additional protein classes: GAP (GTPase-activating)- and GEF (Guanine nucleotide exchange factors)-proteins. The complex interplay of the proteins is known as the GTPase-cycle. Several point mutations of the Ras protein deregulate this cycle. Mutations in Ras are associated with up to one-third of human cancers. The three isoforms of Ras (H, N, K) exhibit high sequence similarity and mainly differ in a region called HVR (hypervariable region). The HVR governs the differential action and cellular distribution of the three isoforms. Rheb is a Ras-like GTPase that is conserved from yeast to mammals. Rheb is mainly involved in activation of cell growth through stimulation of mTORC1 activity. In this review, we summarise multidimensional NMR studies on Rheb and Ras carried out to characterise their structure-function relationship and explain how the activity of these small GTPases can be modulated by low molecular weight compounds. These might help to design GTPase-selective antagonists for treatment of cancer and brain disease.

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