The ATP-binding and ATPase activities of human papillomavirus type 16 E1 are significantly weakened by the absence of prolines in its ATP-binding domain

Raj, Kenneth; Stanley, Margaret

doi:10.1099/0022-1317-76-12-2949

Cited by 13 publications

(11 citation statements)

References 21 publications

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“…E1 is expressed throughout the HPV life cycle; however, the highest levels of E1 expression have been shown to occur during the vegetative stage of the viral life cycle when the late promoter is active [17,20]. The E1 protein is a site-specific DNA-binding protein that possesses ATPase activity [96,97]. It functions as an ATPdependent helicase to catalyse the unwinding of DNA and has been shown to bind DNA polymerase alpha primase subunits to recruit replication machinery to viral origins [98,99].…”

Section: The Replication Proteins E1 and E2mentioning

confidence: 99%

Human papillomaviruses: basic mechanisms of pathogenesis and oncogenicity

Hebner

Laimins

2005

Reviews in Medical Virology

316

251

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Human papillomaviruses (HPVs) are small double-stranded DNA viruses that infect the cutaneous and mucosal epithelium. Infection by specific HPV types has been linked to the development of cervical carcinoma. HPV infects epithelial cells that undergo terminal differentiation and so encode multiple mechanisms to override the normal regulation of differentiation to produce progeny virions. Two viral proteins, E6 and E7, alter cell cycle control and are the main arbitrators of HPV-induced oncogenesis. Recent data suggest that E6 and E7 also play a major role in the inhibition of the host cell innate immune response to HPV. The E1 and E2 proteins, in combination with various cellular factors, mediate viral replication. In addition, E2 has been implicated in both viral and cellular transcriptional control. Despite decades of research, the function of other viral proteins still remains unclear. While prophylactic vaccines to block genital HPV infection will soon be available, the widespread nature of HPV infection requires greater understanding of both the HPV life cycle as well as the mechanisms underlying HPV-induced carcinogenesis.

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Section: The Replication Proteins E1 and E2mentioning

confidence: 99%

Human papillomaviruses: basic mechanisms of pathogenesis and oncogenicity

Hebner

Laimins

2005

Reviews in Medical Virology

316

251

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“…Very low levels of expression, compounded by proteolysis and contamination with other proteins, have commonly been observed. Of the few reports on the isolation of HPV E1 (42,(47)(48)(49), in only one case was sufficient material obtained for a basic characterization of helicase activity and biophysical properties (42). Kuo et al (50) have reported the isolation of epitope-tagged HPV11 E1 that is functional for in vitro DNA replication assays, but the enzymatic activities of their E1 preparations have not been described.…”

Section: From the Department Of Biological Sciences Boehringer Ingelmentioning

confidence: 99%

Characterization of Recombinant HPV6 and 11 E1 Helicases

White

Pelletier

Brault

et al. 2001

Journal of Biological Chemistry

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To better characterize the enzymatic activities required for human papillomavirus (HPV) DNA replication, the E1 helicases of HPV types 6 and 11 were produced using a baculovirus expression system. The purified wild type proteins and a version of HPV11 E1 lacking the N-terminal 71 amino acids, which was better expressed, were found to be hexameric over a wide range of concentrations and to have helicase and ATPase activities with relatively low values for K m (ATP) of 12 M for HPV6 E1 and 6 M for HPV11 E1. Interestingly, the value of K m (ATP) was increased 7-fold in the presence of the E2 transactivation domain. In turn, ATP was found to perturb the co-operative binding of E1 and E2 to DNA. Mutant and truncated versions of in vitro translated E1 were used to identify a minimal ATPase domain composed of the C-terminal 297 amino acids. This fragment was expressed, purified, and found to be fully active in ATP hydrolysis, single-stranded DNA binding, and unwinding assays, despite lacking the minimal origin-binding domain.The papillomaviruses (PVs) 1 are small, nonenveloped DNA viruses that infect and replicate in the cutaneous or mucosal epithelia of humans and other mammals. There are over 100 types of human papillomavirus (HPV), which cause conditions ranging from plantar warts (HPV1) and genital warts (HPV6 and -11) to cervical cancer (HPV16, -18, and -31). HPV6 and -11 are also responsible for laryngeal papillomatosis, a rare but very serious infection of the respiratory tract (1). Antiviral agents capable of specifically inhibiting PV replication could play an important role in the treatment of these diseases, but none exist at this time.Despite their host and tissue specificity, all of the PV types share a common genomic organization. The closed, circular genome of ϳ8000 base pairs codes for only 10 proteins: eight early proteins termed E1-E8 and two late proteins, L1 and L2, that make up the viral coat (2). E1 and E2 are the only viral proteins required for HPV DNA replication (3, 4). E2 is a sequence-specific DNA-binding protein that serves to regulate both transcription and DNA replication. E1, a DNA helicase, is the only PV protein that possesses enzymatic activity (5) and is also the most highly conserved of the PV proteins. For these reasons, E1 has been considered as the most attractive molecular target for the development of antiviral agents (6).During the initiation of PV DNA replication, E2 serves as a specificity factor to enhance binding of E1 monomers to the origin, which by themselves bind to double-stranded DNA with little sequence specificity (4, 7-11). E2 dimers bind with high specificity to DNA sequences within the origin and recruit to it E1 monomers, through direct protein-protein interactions (12, 13). Upon binding to DNA, E1 monomers assemble into hexamers (14, 15), but the E1-E2 interaction is not maintained (16,17). Thus, the role of E2 is to catalyze the assembly of hexameric E1 complexes specifically at the origin. ATP hydrolysis is also required for E1 hexamers to distort the orig...

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“…It is because of this property of proline and the position of the variant, it can be postulated that the substitution of proline with leucine reduce the ability of protein to bind ATP and eventual reduction in the ATP7B protein transport the copper outside the manufacturer's hepatocyte. This assumption was previously proposed by Raj and Stanley (1995) who demonstrated that the ATP binding activity of the protein was significantly weakened by the absence of proline in its ATP-binding domain. The amino acid substitution implied in this mutation was predicted to be very deleterious for the protein function.…”

mentioning

confidence: 65%