Streptococcus mutans GlnK protein: an unusual PII family member

Streptococcus mutans is a Gram-positive bacterium present in the oral cavity, and is considered to be one of the leading causes of dental caries. S. mutans has a glnK gene, which codes for a PII-like protein that is possibly involved in the integration of carbon, nitrogen and energy metabolism in several organisms. To characterize the GlnK protein of S. mutans, the glnK gene was amplified by PCR, and cloned into the expression vectors pET29a(+) and pET28b(+). The native GlnK-Sm was purified by anion exchange (Q-Sepharose) and affinity (Hi-Trap Heparin) chromatography. The GlnK-His-Sm protein was purified using a Hi-Trap Chelating-Ni2+ column. The molecular mass of the GlnK-His-Sm proteins was 85 kDa as determined by gel filtration, indicating that this protein is a hexamer in solution. The GlnK-His-Sm protein is not uridylylated by the Escherichia coli GlnD protein. The activities of the GlnK-Sm and GlnK-His-Sm proteins were assayed in E. coli constitutively expressing the Klebsiella pneumoniae nifLA operon. In K. pneumoniae, NifL inhibits NifA activity in the presence of high ammonium levels and the GlnK protein is required to reduce the inhibition of NifL in the presence of low ammonium levels. The GlnK-Sm protein was unable to reduce NifL inhibition of NifA protein. Surprisingly, the GlnK-His-Sm protein was able to partially reduce NifL inhibition of the NifA protein under nitrogen-limiting conditions, in a manner similar to the GlnK protein of E. coli. These results suggested that S. mutans GlnK is functionally different from E. coli PII proteins.

1.° Passio sancti Emani et sociorum. — 2.° Vita S. Martialis, Episcopi et Confessoris. — 3.° Frodoardi, Presbyteri, chronicon de gestis Normannorum, ab anno 919. ad an. 966. quod anonymus produxit ad annum 978. — 4.° Passio sanctorum Pontificum Saviniani, Potentiani et sociorum. — 5.° Vita Caroli Magni : authore Eginhardo. — 6.° Vita Ludovici Pii, Imperatoris. — 7.° Vita sanctae Mariae Aegyptiae. — 8.° Haimonis, Halberstadiensis, commentarius in Apocalypsim.

Colbertinus

1.° Aimoini, Monachi Floriacensis, historia Francorum, libris quatuor, à Pharamundo ad annum 825. sive ipse Aimoinus, sive alius ad id temporis hanc historiam produxerit. — 2.° Vita Caroli Magni : authore Eginardo. — 3.° Vita Caroli Magni : authore Turpino. — 4.° Gesta Ludovici Pii, Imperatoris : accedit appendix eorum quae sub imperio filiorum ejus et Regum successorum gesta sunt usque ad mortem Philippi I. — 5.° Vita Ludovici VI. cognomento Grossi : authore Sugerio, Abbate. — 6.° Gesta Ludovici VII. Regis Francorum. — 7.° Gesta Philippi Augusti : authore Rigordo, Chronographo ejus. — 8.° Gesta Ludovici VIII. Regis Francorum. — 9.° Gesta Ludovici IX. Regis Francorum : authore Fratre Guillelmo de Nangiaco. — 10.° Gesta Philippi III. eodem authore. — 11.° Provinciale Ecclesiae Romanae.

Colbertinus

1.° Fragmentum annalium Eginhardi. — 2.° Vita Caroli Magni : eodem authore. — 3.° Vita Ludovici, cognomento Pii. — 4.° Narratio de electione Abbatum Vosiensium. — 5.° Regulae Canonicorum libri tres : authore Amalario, Metensi. — 6.° Regula epistolarum formatarum. — 7.° Collationes Cassiani : insertus catalogus monasteriorum dependentium à monasterio sancti Martialis Lemovicensis.

Colbertinus

1.° Vita Caroli Magni : authore Eginhardo ; praemittitur alia ejusdem Caroli vita : authore anonymo. — 2.° Fragmentum chronici Turpini, Rhemensis Archiepiscopi. — 3.° Vita Ludovici Pii, Imperatoris : authore anonymo. — 4.° Chronicon Regum Francorum à morte Ludovici Pii, ad annum 1109.

Colbertinus, antea Jacobi Augusti Thuani

Aeneae Sylvii, postea Pii Papae II. historiographica geographia.

DD. de Bethune

Hydration, conformational states and kinetics of yeast hexokinase PII /

The kinetic study of the coupled enzymatic reaction involving monomeric yeast hexokinase PII (HK) and yeast glucose-6-phosphate dehydrogenase (G-6-PDH) yields a Michaelis constant of 0.15 ± 0.01 mM for D-glucose. At pH 8.7 HK is present in monomeric form. The addition of polyethylene glycol (PEG), to the reaction mixture increased the affinity of HK for glucose, independent ofMW of the PEG from 2000 to 10000. The osmotic stress exerted by PEG can be used to measure the change in number of water molecules that accompany enzyme conformational changes (Rand, et al., 1993). Results indicate that the G-6-PDH is not osmotically sensitive and thus, the change in the number of PEG-inaccessible water molecules (ANw) measured in the coupled reaction is only the difference between the glucose-bound and glucosefree conformations of HK. ANw ~ 450 with PEGs of MW > 2000 under conditions for both binding (Reid and Rand, 1997) and kinetic assays. The contribution water may play in the binding of ATP (Km = 0.24 + 0.02 mM) has also been examined. It was found that in this case ANw = (for osmotic pressures < 2.8x10* dynes/cm^), suggesting no additional numbers of waters are displaced when ATP binds to HK. Osmotic pressure experiments were also performed with dimeric HK. It was determined that both the monomeric and dimeric forms of HK give the same ANw under low pressures. If this large ANw is due to conformational flexibility, it would appear that the flexibility is not reduced upon dimerization ofthe enzyme.

Catechismus ad parochos ex decreto Sacr. Concilii Tridentni Jussu PII. Pontif. Maximi editus, adjetis variantibus.

UANL

Breviarium romanum exdecreto sacrosancti concilii tridentini restitutum S. PII V. Pontificis maximi jussu editum x Clementis VIII primum, nunc denuo Urbani PP. VIII auctoritate recognitum.

UANL

Officium novissimun in festo immaculate conceptions beatae Maríae Virginis PII IX Pontificis maximi Jussu a venerabili clero seculari et regulari in toto orbe unice recitandum.

UANL

Erectio canonica sanctae ecclesiae cathedralis Leonensis Juxta bullam Sanctissimi domni nostri pii papae noni, ynfra transcriptam.

UANL

Catechismus ex decreto Concilii Tridentini ad Parochos, S. Pii V. Pontificis Maximi et deinde Clementis XIII. jussu editus nunc ad fidem Manutiani textus juxta editionem quae anno M. DCCC. LXXI. prodiit ex typis S. Congr. de Propag. Fide neconon alia complura authentica exemplariaiteratis curis castigate impressus

UANL

Catechismos Concilii Tridentini PII V, Pontificis Maxi Jessu promulgatus... approbatores et usus declarantur.

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Breviarium romanum ex decreto SS. concilii tridentini restitutum , S. Pii V. Pontif. Max jussu editum, Clementis VIII, Urbani VIII. et Leonis XIII.

UANL