The catalytic mechanism of protein tyrosine phosphatases revisited

Kolmodin, Karin; Åqvist, Johan

doi:10.1016/s0014-5793(01)02479-6

Cited by 95 publications

(85 citation statements)

References 55 publications

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“…amino acid substrates, recombinant LipA specifically dephosphorylated P-Tyr. Typically, tyrosine-specific phosphatases display a bell-shaped pH rate profile with a low pH optimum (30). In line with this, LipA had its highest activity at pH 6.5.…”

Section: Fig 7 Effect Of L Monocytogenesmentioning

confidence: 62%

LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes

et al. 2011

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Intracellular bacterial pathogens manipulate host cell functions by producing enzymes that stimulate or antagonize signal transduction. TheListeria monocytogenesgenome contains a gene,lmo1800, encoding a protein with a conserved motif of conventional tyrosine phosphatases. Here, we report that thelmo1800-encoded protein LipA is secreted byListeriaand displays tyrosine as well as lipid phosphatase activityin vitro. Bacteria lacking LipA are severely attenuated in virulencein vivo, thus revealing a so-far-undescribed enzymatic activity involved inListeriainfection.

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Section: Fig 7 Effect Of L Monocytogenesmentioning

confidence: 62%

LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes

et al. 2011

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“…PTPs are traditionally classified into four subfamilies (Kolmodin & Å qvist, 2001) : (i) tyrosinespecific phosphatase (which form the main group of this family), (ii) dual-specificity phosphatase (DSP), (iii) low molecular weight PTPs and (iv) dual-specific cdc25 phosphatases. These enzymes differ in sequence and topology, and also whether they are cytosolic or membrane bound, but, with the exception of the cdc25 phosphatases, which have one residue substitution, all contain the characteristic (H/V)CX 5 R(S/T) sequence (Kolmodin & Å qvist, 2001).…”

Section: Protein Tyrosine Phosphatases (Ptps)mentioning

confidence: 99%

“…Evans et al 1996 ;Zhang et al 1994Zhang et al , 1999. However, as discussed also in (Kolmodin & Å qvist, 2001), the qualitative interpretation of such profiles is extremely challenging, as multiple ionizable groups are involved in the process, making it hard to make unambiguous assignments. Nevertheless, the work of e.g.…”

Section: Protein Tyrosine Phosphatases (Ptps)mentioning

confidence: 99%

Why nature really chose phosphate

Kamerlin

Sharma

Prasad

et al. 2013

Quart. Rev. Biophys.

340

448

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Phosphoryl transfer plays key roles in signaling, energy transduction, protein synthesis, and maintaining the integrity of the genetic material. On the surface, it would appear to be a simple nucleophile displacement reaction. However, this simplicity is deceptive, as, even in aqueous solution, the low-lying d-orbitals on the phosphorus atom allow for eight distinct mechanistic possibilities, before even introducing the complexities of the enzyme catalyzed reactions. To further complicate matters, while powerful, traditional experimental techniques such as the use of linear free-energy relationships (LFER) or measuring isotope effects cannot make unique distinctions between different potential mechanisms. A quarter of a century has passed since Westheimer wrote his seminal review, ‘Why Nature Chose Phosphate’ (Science 235 (1987), 1173), and a lot has changed in the field since then. The present review revisits this biologically crucial issue, exploring both relevant enzymatic systems as well as the corresponding chemistry in aqueous solution, and demonstrating that the only way key questions in this field are likely to be resolved is through careful theoretical studies (which of course should be able to reproduce all relevant experimental data). Finally, we demonstrate that the reason that naturereallychose phosphate is due to interplay between two counteracting effects: on the one hand, phosphates are negatively charged and the resulting charge-charge repulsion with the attacking nucleophile contributes to the very high barrier for hydrolysis, making phosphate esters among the most inert compounds known. However, biology is not only about reducing the barrier to unfavorable chemical reactions. That is, the same charge-charge repulsion that makes phosphate ester hydrolysis so unfavorable also makes it possible to regulate, by exploiting the electrostatics. This means that phosphate ester hydrolysis can not only be turned on, but also be turned off, by fine tuning the electrostatic environment and the present review demonstrates numerous examples where this is the case. Without this capacity for regulation, it would be impossible to have for instance a signaling or metabolic cascade, where the action of each participant is determined by the fine-tuned activity of the previous piece in the production line. This makes phosphate esters the ideal compounds to facilitate life as we know it.

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“…Protein-tyrosine phosphatases (PTPs) 2 constitute the largest family of phosphatases. These enzymes are defined by their active-site signature motif, (H/V)CX 5 R(S/T), in which the nucleophilic Cys residue attacks the phosphate group of target proteins (1)(2)(3). Of ϳ100 phosphatase genes classified into the PTP family in the human genome, the most diverse group, in terms of the substrate specificity, is the group of dual-specificity phosphatases (DSPs) (4).…”

mentioning

confidence: 99%

Molecular Dissection of the Mechanisms of Substrate Recognition and F-actin-mediated Activation of Cofilin-phosphatase Slingshot-1

Kurita

Watanabe

Gunji

et al. 2008

Journal of Biological Chemistry

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Slingshot-1 (SSH1), a member of a dual-specificity protein phosphatase family, regulates actin dynamics by dephosphorylating and reactivating cofilin, an actin-depolymerizing factor. SSH1 has the SSH family-specific, N-terminal, noncatalytic (SSH-N) domain, consisting of the A and B subdomains. SSH1 is activated by binding to actin filaments. In this study, we examined the mechanisms of SSH1 substrate recognition of phosphocofilin (P-cofilin) and SSH1 activation by F-actin. We found that P-cofilin binds to a phosphatase-inactive mutant, SSH1(CS), in which the catalytic Cys-393 is replaced by Ser. Using a series of deletion mutants, we provided evidence that both the phosphatase (P) domain and the adjacent B domain are indispensable for P-cofilin binding of SSH1(CS) and cofilin-phosphatase activity of SSH1. In contrast, the A domain is required for the F-actinmediated activation of SSH1, but not for P-cofilin binding or basal cofilin-phosphatase activity. The P domain alone is sufficient for the phosphatase activity toward p-nitrophenyl phosphate (pNPP), indicating that the SSH-N domain is not essential for the basal phosphatase activity of SSH1. Addition of F-actin increased the cofilin-phosphatase activity of SSH1 more than 1200-fold, but the pNPP-phosphatase activity only 2.2-fold, which suggests that F-actin principally affects the cofilin-specific phosphatase activity of SSH1. When expressed in cultured cells, SSH1, but not its mutant deleted of SSH-N, accumulated in the rear of the lamellipodium. Together, these findings suggest that the conserved SSH-N domain plays critical roles in P-cofilin recognition, F-actin-mediated activation, and subcellular localization of SSH1.Protein phosphorylation is one of the most ubiquitous types of post-translational protein modification and is essential for signaling pathways mediating diverse cellular processes. Protein phosphorylation is regulated by the balanced actions of protein kinases and protein phosphatases. Protein-tyrosine phosphatases (PTPs) 2 constitute the largest family of phosphatases. These enzymes are defined by their active-site signature motif, (H/V)CX 5 R(S/T), in which the nucleophilic Cys residue attacks the phosphate group of target proteins (1-3). Of ϳ100 phosphatase genes classified into the PTP family in the human genome, the most diverse group, in terms of the substrate specificity, is the group of dual-specificity phosphatases (DSPs) (4). DSPs are further divided into several subgroups, each having a wide range of substrate specificities for phospho-Ser, phosphoThr, phosphoinositide, and mRNA, in addition to phospho-Tyr (3, 4). These phosphatases play specific roles in decreasing the phosphorylation levels of target molecules and controlling signal transduction pathways that underlie a variety of physiological processes.Cofilin is a key regulator of actin filament dynamics and functions by stimulating the depolymerization and severance of actin filaments (5). Cofilin activity is regulated by its specific kinases and phosphatases. Cofilin is in...

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The catalytic mechanism of protein tyrosine phosphatases revisited

Cited by 95 publications

References 55 publications

LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes

LipA, a Tyrosine and Lipid Phosphatase Involved in the Virulence of Listeria monocytogenes

Why nature really chose phosphate

Molecular Dissection of the Mechanisms of Substrate Recognition and F-actin-mediated Activation of Cofilin-phosphatase Slingshot-1

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