| Id |
Subject |
Object |
Predicate |
Lexical cue |
| T1 |
0-81 |
Sentence |
denotes |
A K319N/E325Q double mutant of the lactose permease cotransports H+ with lactose. |
| T2 |
82-142 |
Sentence |
denotes |
Implications for a proposed mechanism of H+/lactose symport. |
| T3 |
143-401 |
Sentence |
denotes |
In this study, we have examined the transport characteristics of the wild-type lactose permease, single mutants in which Lys-319 was changed to asparagine or alanine or Glu-325 was changed to glutamine or alanine, and the corresponding double mutant strains. |
| T4 |
402-590 |
Sentence |
denotes |
The wild-type and Asn-319 mutant showed high levels of lactose uptake, with Km values of 0.42 and 1.30 mM and Vmax values of 102.6 and 48.3 nmol of lactose/min/mg of protein, respectively. |
| T5 |
591-707 |
Sentence |
denotes |
The Asn-319/Gln-325 strain had a normal Km of 0.36 mM and a moderate Vmax of 18.5 nmol of lactose/min/mg of protein. |
| T6 |
708-841 |
Sentence |
denotes |
By comparison, the single E325Q strain had a normal Km of 0.27 mM but a very defective Vmax of 1.3 nmol of lactose/min/mg of protein. |
| T7 |
842-985 |
Sentence |
denotes |
A similar trend was observed among the alanine substitutions at these positions, although the Vmax values were lower for the Ala-319 mutations. |
| T8 |
986-1214 |
Sentence |
denotes |
When comparing the Vmax values between the single position 325 mutants with those of the double mutants, these results indicate that neutral 319 mutations substantially alleviate a defect in Vmax caused by neutral 325 mutations. |
| T9 |
1215-1339 |
Sentence |
denotes |
With regard to H+/lactose coupling, the wild-type permease is normally coupled and can transport lactose against a gradient. |
| T10 |
1340-1502 |
Sentence |
denotes |
The position 325 single mutants showed no evidence of H+ transport with lactose or thiodigalactoside (TDG) and were unable to facilitate uphill lactose transport. |
| T11 |
1503-1625 |
Sentence |
denotes |
The single Asn-319 mutant and double Asn-319/Gln-325 mutant were able to transport H+ upon the addition of lactose or TDG. |
| T12 |
1626-1747 |
Sentence |
denotes |
In addition, both of these strains catalyzed a sugar-dependent H+ leak that inhibited cell growth in the presence of TDG. |
| T13 |
1748-1866 |
Sentence |
denotes |
These two strains were also defective in uphill transport, which may be related to their sugar-dependent leak pathway. |
| T14 |
1867-2094 |
Sentence |
denotes |
Based on these and other results in the literature, a model is presented that describes how the interactions among several ionizable residues within the lactose permease act in a concerted manner to control H+/lactose coupling. |
| T15 |
2095-2241 |
Sentence |
denotes |
In this model, Lys-319 and Glu-325 play a central role in governing the ability of the lactose permease to couple the transport of H+ and lactose. |
